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{{Short description|Diode that emits light from an organic compound}}
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{{Use dmy dates|date=August 2019}}
{{Infobox electronic component
| name              = Organic light-emitting diode
| image             = OEL right.JPG
| caption           = Prototype OLED lighting panels
| type              = [[Light-emitting diode|LED]]
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An '''organic light-emitting diode''' ('''OLED'''), also known as '''organic electroluminescent''' ('''organic EL''') '''diode''',<ref>{{cite web |title=Organic EL - R&D |url=https://www.sel.co.jp/en/technology/oled.html |website=[[Shunpei Yamazaki|Semiconductor Energy Laboratory]] |access-date=8 July 2019}}</ref><ref>{{cite web |title=What is organic EL? |url=https://www.idemitsu.com/products/electronic/el/index.html |website=[[Idemitsu Kosan]] |access-date=8 July 2019 |archive-date=8 July 2019 |archive-url=https://web.archive.org/web/20190708160128/https://www.idemitsu.com/products/electronic/el/index.html |url-status=dead }}</ref> is a type of [[light-emitting diode]] (LED) in which the [[emission (electromagnetic radiation)|emissive]] [[electroluminescence|electroluminescent]] layer is an [[organic compound]] film that emits light in response to an electric current. This organic layer is situated between two [[electrode]]s; typically, at least one of these electrodes is transparent. OLEDs are used to create [[digital display]]s in devices such as [[television set|television]] screens, [[computer monitor]]s, and portable systems such as [[smartphone]]s and [[handheld game console]]s. A major area of research is the development of white OLED devices for use in [[solid-state lighting]] applications.<ref>{{cite journal|doi=10.1002/adma.200902148|pmid=20217752|title=Recent Advances in White Organic Light-Emitting Materials and Devices (WOLEDs)|year=2010|last1=Kamtekar|first1=K. T.|last2=Monkman|first2=A. P.|last3=Bryce|first3=M. R.|journal=Advanced Materials|volume=22|pages=572–582|issue=5|bibcode=2010AdM....22..572K |s2cid=205234304}}</ref><ref>{{cite journal|doi=10.1002/adma.200400684|title=White Organic Light-Emitting Devices for Solid-State Lighting|year=2004|last1=D'Andrade|first1=B. W.|last2=Forrest|first2=S. R.|journal=Advanced Materials|volume=16|pages=1585–1595|issue=18|bibcode=2004AdM....16.1585D |s2cid=137230337}}</ref><ref>{{cite journal|doi=10.1109/JDT.2013.2248698|title=White Organic Light-Emitting Diodes for Solid-State Lighting|year=2013|last1=Chang|first1=Yi-Lu|last2=Lu|first2=Zheng-Hong|journal=Journal of Display Technology|volume=PP|page=1|issue=99|bibcode = 2013JDisT...9..459C |s2cid=19503009}}</ref>
There are two main families of OLED: those based on small molecules and those employing [[polymer]]s.  Adding mobile [[ion]]s to an OLED creates a [[light-emitting electrochemical cell]] (LEC) which has a slightly different mode of operation. An OLED display can be driven with a [[Passive matrix addressing|passive-matrix]] (PMOLED) or [[Active matrix|active-matrix]] ([[AMOLED]]) control scheme. In the PMOLED scheme, each row and line in the display is controlled sequentially, one by one,<ref>{{cite web|url=http://www.oled-info.com/pmoled-vs-amoled-whats-difference |title=PMOLED vs AMOLED – what's the difference?|website=Oled-info.com |access-date=2016-12-16 |url-status=live |archive-url=https://web.archive.org/web/20161220213332/http://www.oled-info.com/pmoled-vs-amoled-whats-difference |archive-date=2016-12-20 }}</ref> whereas AMOLED control uses a [[thin-film transistor]] (TFT) backplane to directly access and switch each individual pixel on or off, allowing for higher resolution and larger display sizes. OLEDs are fundamentally different from [[LED]]s, which are based on a [[P–n diode|p-n diode]] [[crystal]]line solid structure. In LEDs, [[Doping (semiconductor)|doping]] is used to create p- and n-regions by changing the conductivity of the host [[semiconductor]]. OLEDs do not employ a crystalline p-n structure. Doping of OLEDs is used to increase radiative efficiency by direct modification of the quantum-mechanical optical recombination rate.  Doping is additionally used to determine the [[wavelength]] of photon emission.<ref name="pears1">{{cite book|last1=Pearsall|first1=Thomas|title=Photonics Essentials, 2nd edition|publisher=McGraw-Hill|date=2010|url=https://www.mheducation.com/highered/product/photonics-essentials-second-edition-pearsall/9780071629355.html|isbn=978-0-07-162935-5|access-date=24 February 2021|archive-date=17 August 2021|archive-url=https://web.archive.org/web/20210817005021/https://www.mheducation.com/highered/product/photonics-essentials-second-edition-pearsall/9780071629355.html|url-status=dead}}</ref>
OLED displays are made in a similar way to LCDs, including manufacturing of several displays on a mother substrate that is later thinned and cut into several displays. Substrates for OLED displays come in the same sizes as those used for manufacturing LCDs. For OLED manufacture, after the formation of TFTs (for active matrix displays), addressable grids (for passive matrix displays), or [[indium tin oxide]] (ITO) segments (for segment displays), the display is coated with hole injection, transport and blocking layers, as well with electroluminescent material after the first two layers, after which ITO or metal may be applied again as a [[cathode]]. Later, the entire stack of materials is encapsulated. The TFT layer, addressable grid, or ITO segments serve as or are connected to the [[anode]], which may be made of ITO or metal.<ref>{{cite web |url=https://www.eurekalert.org/multimedia/pub/98686.php |title=Schematics of OLED Structures with Encapsulation &#91;image&#93; &#124; EurekAlert! Science News |access-date=5 January 2020 |archive-date=17 April 2021 |archive-url=https://web.archive.org/web/20210417032422/https://www.eurekalert.org/multimedia/pub/98686.php |url-status=dead }}</ref> OLEDs can be made flexible and transparent, with [[transparent display]]s being used in smartphones with optical fingerprint scanners and [[flexible display]]s being used in [[foldable smartphone]]s.
== History ==
[[André Bernanose]] and co-workers at the [[Nancy-Université]] in France made the first observations of [[electroluminescence]] in organic materials in the early 1950s. They applied high alternating [[voltage]]s in air to materials such as [[acridine orange]] dye, either deposited on or dissolved in [[cellulose]] or [[cellophane]] [[thin film]]s.  The proposed mechanism was either direct excitation of the dye molecules or [[Electron excitation|excitation of electrons]].<ref>{{cite journal|author= Bernanose, A.|author2= Comte, M.|author3 = Vouaux, P. |journal= J. Chim. Phys.|year = 1953|volume= 50|page= 64|title= A new method of light emission by certain organic compounds|doi= 10.1051/jcp/1953500064}}</ref><ref>{{cite journal|author= Bernanose, A. |author2 = Vouaux, P.|journal= J. Chim. Phys.|year= 1953|volume= 50|page= 261|title= Organic electroluminescence type of emission|doi = 10.1051/jcp/1953500261}}</ref><ref>{{cite journal|author= Bernanose, A.|journal= J. Chim. Phys.|year= 1955|volume= 52|page= 396|title= The mechanism of organic electroluminescence|doi= 10.1051/jcp/1955520396}}</ref><ref>{{cite journal|author1=Bernanose, A.  |author2=Vouaux, P. |name-list-style=amp |journal= J. Chim. Phys.|year= 1955|volume= 52|page= 509|title=Relation between organic electroluminescence and concentration of active product}}</ref>
In 1960, [[Martin Pope]] and some of his co-workers at [[New York University]] in the United States developed [[Ohmic contact|ohmic]] dark-injecting electrode contacts to organic crystals.<ref>{{cite journal|doi= 10.1063/1.1700925|title= Positive Hole Injection into Organic Crystals|year= 1960|last1= Kallmann|first1= H.|last2= Pope|first2= M.|journal= The Journal of Chemical Physics|volume= 32|issue= 1|page= 300|author-link2= Martin Pope|bibcode = 1960JChPh..32..300K }}</ref><ref>{{cite journal|doi= 10.1038/186031a0|title= Bulk Conductivity in Organic Crystals|year= 1960|last1= Kallmann|first1= H.|last2= Pope|first2= M.|journal= Nature|volume= 186|pages= 31–33|issue= 4718|bibcode = 1960Natur.186...31K |s2cid= 4243929}}</ref><ref>{{cite journal|doi= 10.1063/1.1728487|title= Space-Charge-Limited Currents in Organic Crystals|year= 1962|last1= Mark|first1= Peter|last2= Helfrich|first2= Wolfgang|journal= Journal of Applied Physics|volume= 33|issue= 1|page= 205|bibcode = 1962JAP....33..205M }}</ref> They further described the necessary energetic requirements ([[work function]]s) for hole and electron injecting electrode contacts. These contacts are the basis of charge injection in all modern OLED devices. Pope's group also first observed direct current (DC) electroluminescence under vacuum on a single pure crystal of [[anthracene]] and on anthracene crystals doped with [[tetracene]] in 1963<ref>{{cite journal|doi= 10.1063/1.1733929|title= Electroluminescence in Organic Crystals|year= 1963|last1= Pope|first1= M.|last2= Kallmann|first2= H. P.|last3= Magnante|first3= P.|journal= The Journal of Chemical Physics|volume= 38|page= 2042|issue= 8|bibcode = 1963JChPh..38.2042P }}</ref> using a small area silver electrode at 400 [[volt]]s. The proposed mechanism was field-accelerated electron excitation of molecular fluorescence.
Pope's group reported in 1965<ref>{{cite journal|doi= 10.1063/1.1697243|title= Electroluminescence and Band Gap in Anthracene|year= 1965|last1= Sano|first1= Mizuka|last2= Pope|first2= Martin|last3= Kallmann|first3= Hartmut|journal= The Journal of Chemical Physics|volume= 43|page= 2920|issue= 8|bibcode = 1965JChPh..43.2920S }}</ref> that in the absence of an external electric field, the electroluminescence in anthracene crystals is caused by the recombination of a thermalized electron and hole, and that the conducting level of anthracene is higher in energy than the [[exciton]] energy level. Also in 1965, [[Wolfgang Helfrich]] and W. G. Schneider of the [[National Research Council (Canada)|National Research Council]] in Canada produced double injection recombination electroluminescence for the first time in an anthracene single crystal using hole and electron injecting electrodes,<ref>{{cite journal|doi= 10.1103/PhysRevLett.14.229|title= Recombination Radiation in Anthracene Crystals|year= 1965|last1= Helfrich|first1= W.|last2= Schneider|first2= W.|journal= Physical Review Letters|volume= 14|pages= 229–231|bibcode= 1965PhRvL..14..229H|issue= 7}}</ref> the forerunner of modern double-injection devices. In the same year, [[Dow Chemical]] researchers patented a method of preparing electroluminescent cells using high-voltage (500–1500 V) AC-driven (100–3000{{nbsp}}Hz) electrically insulated one millimetre thin layers of a melted phosphor consisting of ground anthracene powder, tetracene, and [[graphite]] powder.<ref>Gurnee, E. and Fernandez, R. "Organic electroluminescent phosphors", {{US patent|3172862}}, Issue date: 9 March 1965</ref> Their proposed mechanism involved electronic excitation at the contacts between the graphite particles and the anthracene molecules.
The first Polymer LED (PLED) to be created was by Roger Partridge at the [[National Physical Laboratory (United Kingdom)|National Physical Laboratory]] in the United Kingdom. It used a film of [[polyvinylcarbazole]] up to 2.2 micrometers thick located between two charge-injecting electrodes. The light generated was readily visible in normal lighting conditions though the polymer used had 2 limitations; low conductivity and the difficulty of injecting electrons.<ref>{{cite journal | doi=10.1088/2058-7058/14/1/21 | title=Friend and rival | date=2001 | last1=Partridge | first1=Roger | journal=Physics World | volume=14 | page=20 }}</ref> Later development of conjugated polymers would allow others to largely eliminate these problems. His contribution has often been overlooked due to the secrecy NPL imposed on the project. When it was patented in 1974<ref>Partridge, Roger Hugh, "Radiation sources" {{US Patent|3995299}}, Issue date: 30 November 1976</ref> it was given a deliberately obscure "catch all" name while the government's Department for Industry tried and failed to find industrial collaborators to fund further development.<ref>{{cite journal | doi=10.1098/rsta.2009.0247 | title=Flat-panel electronic displays: A triumph of physics, chemistry and engineering | date=2010 | last1=Hilsum | first1=Cyril | journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | volume=368 | issue=1914 | pages=1027–1082 | pmid=20123746 | pmc=3263809 }}</ref><ref>{{cite journal|doi= 10.1016/0032-3861(83)90012-5|title= Electroluminescence from polyvinylcarbazole films: 1. Carbazole cations|year= 1983|last1= Partridge|first1= R|journal= Polymer|volume= 24|pages= 733–738|issue= 6}}</ref><ref>{{cite journal|doi= 10.1016/0032-3861(83)90013-7|title= Electroluminescence from polyvinylcarbazole films: 2. Polyvinylcarbazole films containing antimony pentachloride|year= 1983|last1= Partridge|first1= R|journal= Polymer|volume= 24|pages= 739–747|issue= 6}}</ref><ref>{{cite journal|doi= 10.1016/0032-3861(83)90014-9|title= Electroluminescence from polyvinylcarbazole films: 3. Electroluminescent devices|year=1983|last1=Partridge|first1=R|journal=Polymer|volume=24|pages=748–754|issue=6}}</ref><ref>{{cite journal|doi= 10.1016/0032-3861(83)90015-0|title= Electroluminescence from polyvinylcarbazole films: 4. Electroluminescence using higher work function cathodes|year= 1983|last1= Partridge|first1= R|journal= Polymer|volume= 24|pages= 755–762|issue= 6}}</ref>
===Practical OLEDs===
Chemists [[Ching Wan Tang]] and [[Steven Van Slyke]] at [[Eastman Kodak]] built the first practical OLED device in 1987.<ref name=ApplPhy87/> This device used a two-layer structure with separate hole transporting and electron transporting layers such that recombination and light emission occurred in the middle of the organic layer; this resulted in a reduction in operating voltage and improvements in efficiency.{{cn|date=July 2024}}
Research into polymer electroluminescence culminated in 1990, with J. H. Burroughesat the [[Cavendish Laboratory]] at [[Cambridge University]], UK, reporting a high-efficiency green light-emitting polymer-based device using 100{{nbsp}}nm thick films of [[poly(p-phenylene vinylene)]].<ref name="b">{{cite journal|doi= 10.1038/347539a0|url=https://www.nature.com/articles/347539a0|title= Light-emitting diodes based on conjugated polymers|year= 1990|last1= Burroughes|first1= J. H.|last2= Bradley|first2= D. D. C.|last3= Brown|first3= A. R.|last4= Marks|first4= R. N.|last5= MacKay|first5= K.|last6= Friend|first6= R. H.|last7= Burns|first7= P. L.|last8= Holmes|first8= A. B.|journal= Nature|volume= 347|pages= 539–541|issue= 6293|bibcode= 1990Natur.347..539B|s2cid= 43158308}}</ref> Moving from molecular to macromolecular materials solved the problems previously encountered with the long-term stability of the organic films and enabled high-quality films to be easily made.<ref name="b" /> Subsequent research developed multilayer polymers and the new field of [[plastic electronics]] and OLED research and device production grew rapidly.<ref>{{cite book|author1=National Research Council|title=The Flexible Electronics Opportunity|date=2015|publisher=The National Academies Press|isbn=978-0-309-30591-4|pages=105–6|url=http://www.nap.edu/read/18812/chapter/7}}</ref> White OLEDs, pioneered by J. Kido et al. at [[Yamagata University]], Japan in 1995, achieved the commercialization of OLED-backlit displays and lighting.<ref>{{Cite journal|last1=Bobbert|first1=Peter|last2=Coehoorn|first2=Reinder|date=September 2013|title=A look inside white OLEDs|journal=Europhysics News|volume=44|issue=5|pages=21–25|doi=10.1051/epn/2013504|bibcode=2013ENews..44e..21B|issn=0531-7479|doi-access=free}}</ref><ref>{{Cite journal|last1=Kido|first1=J.|last2=Kimura|first2=M.|last3=Nagai|first3=K.|date=1995-03-03|title=Multilayer White Light-Emitting Organic Electroluminescent Device|url=http://dx.doi.org/10.1126/science.267.5202.1332|journal=Science|volume=267|issue=5202|pages=1332–1334|doi=10.1126/science.267.5202.1332|pmid=17812607|bibcode=1995Sci...267.1332K|s2cid=22265451|issn=0036-8075}}</ref>
In 1999, Kodak and [[Sanyo]] had entered into a partnership to jointly research, develop, and produce OLED displays. They announced the world's first 2.4-inch active-matrix, full-color OLED display in September the same year.<ref>{{cite web|url=https://www.eetimes.com/document.asp?doc_id=1144240|title=Sanyo, Kodak ramp OLED production line|date=2001-12-06|website=Eetimes.com}}</ref> In September 2002, they presented a prototype of 15-inch HDTV format display based on white OLEDs with color filters at the CEATEC Japan.<ref>{{cite web|url=https://www.cnet.com/news/kodak-sanyo-demo-oled-display/|title=Kodak, Sanyo demo OLED display|last=Shim|first=Richard|website=Cnet.com|language=en|access-date=2019-10-06}}</ref>
Manufacturing of small molecule OLEDs was started in 1997 by [[Pioneer Corporation]], followed by [[TDK]] in 2001 and [[Samsung]]-[[NEC]] Mobile Display (SNMD), which later became one of the world's largest OLED display manufacturers - Samsung Display, in 2002.<ref>{{cite web|url=https://www.ewh.ieee.org/soc/cpmt/presentations/cpmt0401a.pdf|title=Overview of OLED display technology|last=Antoniadis|first=Homer|website=[[IEEE]]}}</ref>
The [[Sony XEL-1]], released in 2007, was the first OLED television.<ref name="xel1"/> [[Universal Display Corporation]], one of the OLED materials companies, holds a number of patents concerning the commercialization of OLEDs that are used by major OLED manufacturers around the world.<ref>{{cite web|url=https://www.kipost.net/news/articleView.html?idxno=122085|title=Samsung Display renews a license agreement with UDC for OLED patents|date=2018-02-22|website=Kipost.net|language=ko|access-date=2019-11-10}}</ref><ref>{{cite web|url=https://www.koreatimes.co.kr/www/tech/2019/11/133_172534.html|title=LG extends OLED pact with UDC|date=2015-01-27|website=Koreatimes.co.kr|language=en|access-date=2019-11-10}}</ref>
On 5 December 2017, [[JOLED]], the successor of [[Sony]] and [[Panasonic]]'s printable OLED business units, began the world's first commercial shipment of inkjet-printed OLED panels.<ref>{{cite web|url=https://www.printedelectronicsworld.com/articles/13282/joled-begin-commercial-shipment-of-worlds-first-printing-oled-panels|title=JOLED begin commercial shipment of world's first printing OLED Panels|date=2017-12-12|website=Printed Electronics World|language=en|access-date=2019-11-28}}</ref><ref>{{cite web|url=https://www.displaydaily.com/paid-news/ldm-mdm/ldm-mdmfront-page/joled-starts-commercial-shipments-printable-oleds|title=JOLED Starts Commercial Shipments Printable OLEDs|last=Raikes|first=Bob|date=2017-12-08|website=DisplayDaily.com|language=en-gb|access-date=2019-11-28}}</ref>
== Working principle ==
[[File:OLED schematic.svg|thumb|right|400px|Schematic of a bilayer OLED: 1. Cathode (−), 2. Emissive Layer, 3. Emission of radiation, 4. Conductive layer, 5. Anode (+)]]
A typical OLED is composed of a layer of organic materials situated between two electrodes, the [[anode]] and [[cathode]], all deposited on a [[substrate (materials science)|substrate]]. The organic molecules are electrically conductive as a result of [[Delocalized electron|delocalization]] of [[pi electrons]] caused by [[conjugated system|conjugation]] over part or all of the molecule. These materials have conductivity levels ranging from insulators to conductors, and are therefore considered [[organic semiconductor]]s. The highest occupied and lowest unoccupied molecular orbitals ([[HOMO and LUMO]]) of organic semiconductors are analogous to the [[valence band|valence]] and [[Conduction band|conduction]] bands of inorganic semiconductors.<ref name="kho2">Kho, Mu-Jeong, Javed, T., Mark, R., Maier, E., and David, C. (2008) ''Final Report: OLED Solid State Lighting – Kodak European Research,'' MOTI (Management of Technology and Innovation) Project, Judge Business School of the University of Cambridge and Kodak European Research, Final Report presented on 4 March 2008, at Kodak European Research at Cambridge Science Park, Cambridge, UK., pp. 1–12</ref>
Originally, the most basic polymer OLEDs consisted of a single organic layer. One example was the first light-emitting device synthesised by J. H. Burroughes ''et al.'', which involved a single layer of [[poly(p-phenylene vinylene)]]. However multilayer OLEDs can be fabricated with two or more layers in order to improve device efficiency. As well as conductive properties, different materials may be chosen to aid charge injection at electrodes by providing a more gradual electronic profile,<ref>{{cite journal|doi=10.1063/1.1317547|title=Role of CsF on electron injection into a conjugated polymer|year=2000|last1=Piromreun|first1=Pongpun|last2=Oh|first2=Hwansool|last3=Shen|first3=Yulong|last4=Malliaras|first4=George G.|last5=Scott|first5=J. Campbell|last6=Brock|first6=Phil J.|journal=Applied Physics Letters|volume=77|page=2403|issue=15|bibcode = 2000ApPhL..77.2403P }}</ref> or block a charge from reaching the opposite electrode and being wasted.<ref>D. Ammermann, A. Böhler, W. Kowalsky, [http://www.tu-braunschweig.de/Medien-DB/ihf/p048-058.pdf ''Multilayer Organic Light Emitting Diodes for Flat Panel Displays''] {{webarchive|url=https://web.archive.org/web/20090226195658/http://www.tu-braunschweig.de/Medien-DB/ihf/p048-058.pdf |date=2009-02-26 }}, Institut für Hochfrequenztechnik, TU Braunschweig, 1995.</ref> Many modern OLEDs incorporate a simple bilayer structure, consisting of a conductive layer and an emissive layer.  Developments in OLED architecture in 2011 improved [[quantum efficiency]] (up to 19%) by using a graded heterojunction.<ref name=r2>{{cite web|url=http://www.license.umn.edu/Products/Organic-Light-Emitting-Diodes-Based-on-Graded-Heterojunction-Architecture-Has-Greater-Quantum-Efficiency__20100200.aspx |publisher=University of Minnesota |access-date=31 May 2011 |title=Organic Light-Emitting Diodes Based on Graded Heterojunction Architecture Has Greater Quantum Efficiency |url-status=dead |archive-url=https://web.archive.org/web/20120324152059/http://www.license.umn.edu/Products/Organic-Light-Emitting-Diodes-Based-on-Graded-Heterojunction-Architecture-Has-Greater-Quantum-Efficiency__20100200.aspx |archive-date=24 March 2012 }}</ref> In the graded heterojunction architecture, the composition of hole and electron-transport materials varies continuously within the emissive layer with a dopant emitter. The graded heterojunction architecture combines the benefits of both conventional architectures by improving charge injection while simultaneously balancing charge transport within the emissive region.<ref>{{cite journal|last=Holmes|first=Russell|author2=Erickson, N.|title=Highly efficient, single-layer organic light-emitting devices based on a graded-composition emissive layer|journal=Applied Physics Letters|date=27 August 2010|volume=97|issue=1|page=083308|bibcode = 2010ApPhL..97a3308S |doi = 10.1063/1.3460285 |last3=Lüssem|first3=Björn|last4=Leo|first4=Karl}}</ref>
During operation, a voltage is applied across the OLED such that the anode is positive with respect to the cathode. Anodes are picked based upon the quality of their optical transparency, electrical conductivity, and chemical stability.<ref>{{cite journal|last=Lin Ke|first=Peng|author2=Ramadas, K. |author3=Burden, A. |author4=Soo-Jin, C. |title=Indium-tin-oxide-free organic light-emitting device|journal=IEEE Transactions on Electron Devices |date=June 2006|volume=53|issue=6|pages=1483–1486 |doi=10.1109/TED.2006.874724|bibcode=2006ITED...53.1483K|s2cid=41905870}}</ref> A current of [[electron]]s flows through the device from cathode to anode, as electrons are injected into the LUMO of the organic layer at the cathode and withdrawn from the HOMO at the anode. This latter process may also be described as the injection of [[electron hole]]s into the HOMO. Electrostatic forces bring the electrons and the holes towards each other and they recombine forming an [[exciton]], a bound state of the electron and hole. This happens closer to the electron-transport layer part of the emissive layer, because in organic semiconductors holes are generally more [[Semiconductor carrier mobility|mobile]] than electrons.{{fact|date=April 2024}} The decay of this excited state results in a relaxation of the energy levels of the electron, accompanied by emission of [[radiation]] whose [[frequency]] is in the [[visible spectrum|visible region]]. The frequency of this radiation depends on the [[band gap]] of the material, in this case the difference in energy between the HOMO and LUMO.
As electrons and holes are [[fermion]]s with half integer [[Spin (physics)|spin]], an exciton may either be in a [[singlet state]] or a [[triplet state]] depending on how the spins of the electron and hole have been combined. Statistically three triplet excitons will be formed for each singlet exciton. Decay from triplet states ([[phosphorescence]]) is spin forbidden, increasing the timescale of the transition and limiting the internal efficiency of fluorescent OLED emissive layers and devices. [[Phosphorescent organic light-emitting diode]]s (PHOLEDs) or emissive layers make use of [[spin–orbit interaction]]s to facilitate [[intersystem crossing]] between singlet and triplet states, thus obtaining emission from both singlet and triplet states and improving the internal efficiency.
[[Indium tin oxide]] (ITO) is commonly used as the anode material. It is transparent to visible light and has a high [[work function]] which promotes injection of holes into the HOMO level of the organic layer. A second conductive (injection) layer is typically added, which may consist of [[PEDOT:PSS]],<ref>{{cite journal|doi=10.1063/1.118953|year=1997|last1=Carter|first1=S. A.|last2=Angelopoulos|first2=M.|last3=Karg|first3=S.|last4=Brock|first4=P. J.|last5=Scott|first5=J. C.|title=Polymeric anodes for improved polymer light-emitting diode performance|journal=Applied Physics Letters|volume=70|page=2067|issue=16|bibcode = 1997ApPhL..70.2067C }}</ref> as the HOMO level of this material generally lies between the work function of ITO and the HOMO of other commonly used polymers, reducing the energy barriers for hole injection. Metals such as [[barium]] and [[calcium]] are often used for the cathode as they have low [[work function]]s which promote injection of electrons into the LUMO of the organic layer.<ref>{{cite journal|doi=10.1038/16393|year=1999|last1=Friend|first1=R. H.|title=Electroluminescence in conjugated polymers|last2=Gymer|first2=R. W.|last3=Holmes|first3=A. B.|last4=Burroughes|first4=J. H.|last5=Marks|first5=R. N.|last6=Taliani|first6=C.|last7=Bradley|first7=D. D. C.|last8=Santos|first8=D. A. Dos|last9=Brdas|first9=J. L.|last10=Lgdlund|first10=M.|last11=Salaneck|first11=W. R.|journal=Nature|volume=397|pages=121–128|issue=6715|bibcode = 1999Natur.397..121F |s2cid=4328634}}</ref> Such metals are reactive, so they require a capping layer of [[aluminium]] to avoid degradation. Two secondary benefits of the aluminum capping layer include robustness to electrical contacts and the back reflection of emitted light out to the transparent ITO layer.
Experimental research has proven that the properties of the anode, specifically the anode/hole transport layer (HTL) interface topography plays a major role in the efficiency, performance, and lifetime of organic light-emitting diodes.  Imperfections in the surface of the anode decrease anode-organic film interface adhesion, increase electrical resistance, and allow for more frequent formation of non-emissive dark spots in the OLED material adversely affecting lifetime.  Mechanisms to decrease anode roughness for ITO/glass substrates include the use of thin films and self-assembled monolayers.  Also, alternative substrates and anode materials are being considered to increase OLED performance and lifetime.  Possible examples include single crystal sapphire substrates treated with gold (Au) film anodes yielding lower work functions, operating voltages, electrical resistance values, and increasing lifetime of OLEDs.<ref>{{cite journal|title=Spintronic OLEDs could be brighter and more efficient|journal=Engineer (Online Edition)|date=16 July 2012|page=1}}</ref>
Single carrier devices are typically used to study the [[chemical kinetics|kinetics]] and charge transport mechanisms of an organic material and can be useful when trying to study energy transfer processes. As current through the device is composed of only one type of charge carrier, either electrons or holes, recombination does not occur and no light is emitted. For example, electron only devices can be obtained by replacing ITO with a lower work function metal which increases the energy barrier of hole injection. Similarly, hole only devices can be made by using a cathode made solely of aluminium, resulting in an energy barrier too large for efficient electron injection.<ref>{{cite journal|doi=10.1063/1.117530|year=1996|last1=Davids|first1=P. S.|last2=Kogan|first2=Sh. M.|last3=Parker|first3=I. D.|last4=Smith|first4=D. L.|title=Charge injection in organic light-emitting diodes: Tunneling into low mobility materials|journal=Applied Physics Letters|volume=69|page=2270|issue=15|bibcode = 1996ApPhL..69.2270D |url=https://zenodo.org/record/1231842}}</ref><ref>{{cite journal|doi=10.1063/1.122706|year=1998|last1=Crone|first1=B. K.|last2=Campbell|first2=I. H.|last3=Davids|first3=P. S.|last4=Smith|first4=D. L.|title=Charge injection and transport in single-layer organic light-emitting diodes|journal=Applied Physics Letters|volume=73|page=3162|issue=21|bibcode = 1998ApPhL..73.3162C |url=https://zenodo.org/record/1231846}}</ref><ref>{{cite journal|doi=10.1063/1.371591|year=1999|last1=Crone|first1=B. K.|last2=Campbell|first2=I. H.|last3=Davids|first3=P. S.|last4=Smith|first4=D. L.|last5=Neef|first5=C. J.|last6=Ferraris|first6=J. P.|title=Device physics of single layer organic light-emitting diodes|journal=Journal of Applied Physics|volume=86|page=5767|issue=10|bibcode = 1999JAP....86.5767C |url=https://zenodo.org/record/1232057}}</ref>
== Carrier balance ==
Balanced charge injection and transfer are required to get high internal efficiency, pure emission of luminance layer without contaminated emission from charge transporting layers, and high stability. A common way to balance charge is optimizing the thickness of the charge transporting layers but is hard to control. Another way is using the exciplex. Exciplex formed between hole-transporting (p-type) and electron-transporting (n-type) side chains to localize electron-hole pairs. Energy is then transferred to luminophore and provide high efficiency. An example of using exciplex is grafting Oxadiazole and carbazole side units in red diketopyrrolopyrrole-doped Copolymer main chain shows improved external quantum efficiency and color purity in no optimized OLED.<ref>{{cite journal|last1=Jin|first1=Yi|last2=Xu|first2=Yanbin|last3=Qiao|first3=Zhi|last4=Peng|first4=Junbiao|last5=Wang|first5=Baozheng|last6=Cao|first6=Derong|title=Enhancement of Electroluminescence Properties of Red Diketopyrrolopyrrole-Doped Copolymers by Oxadiazole and Carbazole Units as Pendants|journal=Polymer|date=2010|volume=51|issue=24|pages=5726–5733|doi=10.1016/j.polymer.2010.09.046}}</ref>
== Material technologies ==
=== Small molecules ===
[[File:AlumQ3.svg|thumb|upright|[[Tris(8-hydroxyquinolinato)aluminium|Alq<sub>3</sub>]],<ref name=ApplPhy87>{{cite journal|doi=10.1063/1.98799|title=Organic electroluminescent diodes|year=1987|last1=Tang|first1=C. W.|last2=Vanslyke|first2=S. A.|journal=Applied Physics Letters|volume=51|page=913|issue=12|bibcode = 1987ApPhL..51..913T }}</ref> commonly used in small molecule OLEDs]]
Organic small-molecule electroluminescent materials have the advantages of a wide variety, easy to purify, and strong chemical modifications. In order to make the luminescent materials to emit light as required, some chromophores or unsaturated groups such as alkene bonds and benzene rings will usually be introduced in the molecular structure design to change the size of the conjugation range of the material, so that the photophysical properties of the material changes. In general, the larger the range of π-electron conjugation system, the longer the wavelength of light emitted by the material. For instance, with the increase of the number of benzene rings, the fluorescence emission peak of [[benzene]], [[naphthalene]], [[anthracene]],<ref>{{Cite journal |last1=Shah |first1=Bipin K. |last2=Neckers |first2=Douglas C. |last3=Shi |first3=Jianmin |last4=Forsythe |first4=Eric W. |last5=Morton |first5=David |date=2006-02-01 |title=Anthanthrene Derivatives as Blue Emitting Materials for Organic Light-Emitting Diode Applications |url=https://pubs.acs.org/doi/10.1021/cm052188x |journal=Chemistry of Materials |language=en |volume=18 |issue=3 |pages=603–608 |doi=10.1021/cm052188x |issn=0897-4756}}</ref> and tetracene gradually red-shifted from 283&nbsp;nm to 480&nbsp;nm. Common organic small molecule electroluminescent materials include aluminum complexes, [[anthracene]]s, biphenyl acetylene aryl derivatives, coumarin derivatives,<ref name="sciencedirect.com">{{Cite journal |last1=Zhang |first1=Hui |last2=Liu |first2=Xiaochun |last3=Gong |first3=Yuxuan |last4=Yu |first4=Tianzhi |last5=Zhao |first5=Yuling |date=2021-02-01 |title=Synthesis and characterization of SFX-based coumarin derivatives for OLEDs |url=https://www.sciencedirect.com/science/article/pii/S0143720820316661 |journal=Dyes and Pigments |language=en |volume=185 |pages=108969 |doi=10.1016/j.dyepig.2020.108969 |s2cid=228906688 |issn=0143-7208}}</ref> and various fluorochromes. Efficient OLEDs using small molecules were first developed by [[Ching W. Tang]] ''et al.''<ref name="ApplPhy872">{{cite journal |last1=Tang |first1=C. W. |last2=Vanslyke |first2=S. A. |year=1987 |title=Organic electroluminescent diodes |journal=Applied Physics Letters |volume=51 |issue=12 |page=913 |bibcode=1987ApPhL..51..913T |doi=10.1063/1.98799}}</ref> at [[Eastman Kodak]]. The term OLED traditionally refers specifically to this type of device, though the term SM-OLED is also in use.<ref name="kho2"/>
Molecules commonly used in OLEDs include organometallic [[Chelation|chelates]] (for example [[Tris(8-hydroxyquinolinato)aluminium|Alq<sub>3</sub>]], used in the organic light-emitting device reported by Tang ''et al.''), fluorescent and phosphorescent dyes and conjugated [[dendrimer]]s. A number of materials are used for their charge transport properties, for example [[triphenylamine]] and derivatives are commonly used as materials for hole transport layers.<ref>{{cite journal |last1=Bellmann |first1=E. |last2=Shaheen |first2=S. E. |last3=Thayumanavan |first3=S. |last4=Barlow |first4=S. |last5=Grubbs |first5=R. H. |last6=Marder |first6=S. R. |last7=Kippelen |first7=B. |last8=Peyghambarian |first8=N. |year=1998 |title=New Triarylamine-Containing Polymers as Hole Transport Materials in Organic Light-Emitting Diodes: Effect of Polymer Structure and Cross-Linking on Device Characteristics |journal=Chemistry of Materials |volume=10 |issue=6 |pages=1668–1676 |doi=10.1021/cm980030p}}</ref> Fluorescent dyes can be chosen to obtain light emission at different wavelengths, and compounds such as [[perylene]], [[rubrene]] and [[quinacridone]] derivatives are often used.<ref>{{cite journal |last1=Sato |first1=Y. |last2=Ichinosawa |first2=S. |last3=Kanai |first3=H. |year=1998 |title=Operation Characteristics and Degradation of Organic Electroluminescent Devices |journal=IEEE Journal of Selected Topics in Quantum Electronics |volume=4 |issue=1 |pages=40–48 |bibcode=1998IJSTQ...4...40S |doi=10.1109/2944.669464}}</ref> Alq<sub>3</sub> has been used as a green light emitter, electron transport material and as a host for yellow light and red light emitting dyes.
Because of the structural flexibility of small-molecule electroluminescent materials, thin films can be prepared by vacuum vapor deposition, which is more expensive and of limited use for large-area devices. The vacuum coating system, however, can make the entire process from film growth to OLED device preparation in a controlled and complete operating environment, helping to obtain uniform and stable films, thus ensuring the final fabrication of high-performance OLED devices.However, small molecule organic dyes are prone to fluorescence quenching<ref>{{Cite journal |last1=Young |first1=Ralph H. |last2=Tang |first2=Ching W. |last3=Marchetti |first3=Alfred P. |date=2002-02-04 |title=Current-induced fluorescence quenching in organic light-emitting diodes |url=https://aip.scitation.org/doi/10.1063/1.1445271 |journal=Applied Physics Letters |volume=80 |issue=5 |pages=874–876 |doi=10.1063/1.1445271 |bibcode=2002ApPhL..80..874Y |issn=0003-6951}}</ref> in the solid state, resulting in lower luminescence efficiency. The doped OLED devices are also prone to crystallization, which reduces the luminescence and efficiency of the devices. Therefore, the development of devices based on small-molecule electroluminescent materials is limited by high manufacturing costs, poor stability, short life, and other shortcomings. Coherent emission from a laser dye-doped tandem SM-OLED device, excited in the pulsed regime, has been demonstrated.<ref>{{cite journal |last1=Duarte |first1=FJ |author-link1=F. J. Duarte |last2=Liao |first2=LS |last3=Vaeth |first3=KM |year=2005 |title=Coherence characteristics of electrically excited tandem organic light-emitting diodes |journal=Optics Letters |volume=30 |issue=22 |pages=3072–4 |bibcode=2005OptL...30.3072D |doi=10.1364/OL.30.003072 |pmid=16315725}}</ref> The emission is nearly diffraction limited with a spectral width similar to that of broadband dye lasers.<ref>{{cite journal |last1=Duarte |first1=FJ |year=2007 |title=Coherent electrically excited organic semiconductors: visibility of interferograms and emission linewidth |journal=Optics Letters |volume=32 |issue=4 |pages=412–4 |bibcode=2007OptL...32..412D |doi=10.1364/OL.32.000412 |pmid=17356670}}</ref>
Researchers report luminescence from a single polymer molecule, representing the smallest possible organic light-emitting diode (OLED) device.<ref>[http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.112.047403 Synopsis: A Single-Molecule Light-Emitting Diode] {{webarchive|url=https://web.archive.org/web/20140130082032/http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.112.047403|date=2014-01-30}}, Physics, 28 January 2014</ref> Scientists will be able to optimize substances to produce more powerful light emissions. Finally, this work is a first step towards making molecule-sized components that combine electronic and optical properties. Similar components could form the basis of a molecular computer.<ref>[http://www.photonicsonline.com/doc/researchers-develop-first-single-molecule-led-0001 Researchers Develop First Single-Molecule LED] {{webarchive|url=https://web.archive.org/web/20140221185851/http://www.photonicsonline.com/doc/researchers-develop-first-single-molecule-led-0001|date=2014-02-21}}, Photonics Online, 31 January 2014</ref>
=== Polymer light-emitting diodes ===
[[File:Polyphenylene vinylene.svg|thumb|upright|[[poly(p-phenylene vinylene)|poly(''p''-phenylene vinylene)]], used in the first PLED<ref name=b/>]]
Polymer light-emitting diodes (PLED, P-OLED), also light-emitting polymers (LEP), involve an [[electroluminescence|electroluminescent]] [[conductive polymer]] that emits [[light]] when connected to an external voltage. They are used as a [[thin film]] for [[full-spectrum]] colour displays.  Polymer OLEDs are quite efficient and require a relatively small amount of power for the amount of light produced.
Vacuum deposition is not a suitable method for forming thin films of polymers. If the polymeric OLED films are made by vacuum vapor deposition, the chain elements will be cut off and the original photophysical properties will be compromised. However, polymers can be processed in solution, and [[spin coating]] is a common method of depositing thin polymer films. This method is more suited to forming large-area films than thermal evaporation. No vacuum is required, and the emissive materials can also be applied on the [[substrate (printing)|substrate]] by a technique derived from commercial [[inkjet printer|inkjet]] printing.<ref>{{cite journal|doi=10.1063/1.120807|title=Ink-jet printing of doped polymers for organic light emitting devices|year=1998|last1=Hebner|first1=T. R.|last2=Wu|first2=C. C.|last3=Marcy|first3=D.|last4=Lu|first4=M. H.|last5=Sturm|first5=J. C.|journal=Applied Physics Letters|volume=72|page=519|issue=5|bibcode=1998ApPhL..72..519H}}</ref><ref>{{cite journal|doi=10.1063/1.121090|title=Polymer electroluminescent devices processed by inkjet printing: I. Polymer light-emitting logo|year=1998|last1=Bharathan|first1=Jayesh|last2=Yang|first2=Yang|journal=Applied Physics Letters|volume=72|page=2660|issue=21|bibcode=1998ApPhL..72.2660B}}</ref> However, as the application of subsequent layers tends to dissolve those already present, formation of multilayer structures is difficult with these methods. The metal cathode may still need to be deposited by thermal evaporation in vacuum. An alternative method to vacuum deposition is to deposit a [[Langmuir-Blodgett film]].
Typical polymers used in PLED displays include derivatives of [[poly(p-phenylene vinylene)|poly(''p''-phenylene vinylene)]] and [[polyfluorene]]. [[Substitution reaction|Substitution]] of side chains onto the polymer backbone may determine the colour of emitted light<ref>Heeger, A. J. (1993) in W. R. Salaneck, I. Lundstrom, B. Ranby, ''Conjugated Polymers and Related Materials'', Oxford, 27–62. {{ISBN|0-19-855729-9}}</ref> or the stability and solubility of the polymer for performance and ease of processing.<ref>Kiebooms, R.; Menon, R.; Lee, K. (2001) in H. S. Nalwa, ''Handbook of Advanced Electronic and Photonic Materials and Devices Volume 8'', Academic Press, 1–86.</ref>
While unsubstituted poly(p-phenylene vinylene) (PPV) is typically insoluble, a number of PPVs and related poly(naphthalene vinylene)s (PNVs) that are soluble in organic solvents or water have been prepared via [[ring opening metathesis polymerization]].<ref>{{cite journal |first1=Michael | last1= Wagaman |first2= Robert H. |last2=Grubbs|title=Synthesis of PNV Homo- and Copolymers by a ROMP Precursor Route |journal= Synthetic Metals|volume= 84|issue= 1–3| year= 1997|pages=327–328|doi=10.1016/S0379-6779(97)80767-9 }}</ref><ref>{{cite journal |first1=Michael | last1= Wagaman |first2= Robert H. |last2=Grubbs|title=Synthesis of Organic and Water Soluble Poly(1,4-phenylenevinylenes) Containing Carboxyl Groups: Living Ring-Opening Metathesis Polymerization (ROMP) of 2,3-Dicarboxybarrelenes|journal= Macromolecules|year= 1997|volume= 30 |issue=14|pages= 3978–3985| doi = 10.1021/ma9701595 |bibcode = 1997MaMol..30.3978W }}</ref><ref>{{cite journal | first1=Lin|last1= Pu |first2=Michael | last2= Wagaman |first3= Robert H. |last3=Grubbs|title=Synthesis of Poly(1,4-naphthylenevinylenes): Metathesis Polymerization of Benzobarrelenes| journal= Macromolecules|year= 1996|volume= 29 |issue=4|pages= 1138–1143 | doi = 10.1021/ma9500143 | bibcode= 1996MaMol..29.1138P }}</ref> These water-soluble polymers or conjugated poly electrolytes (CPEs) also can be used as hole injection layers alone or in combination with [[nanoparticle]]s like graphene.<ref>{{Cite journal |last1=Fallahi |first1=Afsoon |last2=Alahbakhshi |first2=Masoud |last3=Mohajerani |first3=Ezeddin |last4=Afshar Taromi |first4=Faramarz |last5=Mohebbi |first5=Ali Reza |last6=Shahinpoor |first6=Mohsen |date=2015-06-11 |title=Cationic Water-Soluble Conjugated Polyelectrolytes/Graphene Oxide Nanocomposites as Efficient Green Hole Injection Layers in Organic Light Emitting Diodes |url=https://pubs.acs.org/doi/10.1021/acs.jpcc.5b00863 |journal=The Journal of Physical Chemistry C |language=en |volume=119 |issue=23 |pages=13144–13152 |doi=10.1021/acs.jpcc.5b00863 |issn=1932-7447}}</ref>
=== Phosphorescent materials ===
[[File:Ir(mppy)3.svg|thumb|upright|Ir(mppy)<sub>3</sub>, a phosphorescent dopant which emits green light<ref name=yang>{{cite journal|doi=10.1002/adma.200305621|title=Highly Efficient Single-Layer Polymer Electrophosphorescent Devices|year=2004|last1=Yang|first1=Xiaohui|last2=Neher|first2=Dieter|last3=Hertel|first3=Dirk|last4=Daubler|first4=Thomas|journal=Advanced Materials|volume=16|pages=161–166|issue=2|bibcode=2004AdM....16..161Y |s2cid=97006074|doi-access=free}}</ref>]]
{{Main|Phosphorescent organic light-emitting diode}}
Phosphorescent organic light-emitting diodes use the principle of electrophosphorescence to convert electrical energy in an OLED into light in a highly efficient manner,<ref name=baldo>{{cite journal|doi=10.1038/25954|title=Highly Efficient phosphorescent emission from organic electroluminescent devices|year=1998|last1=Baldo|first1=M. A.|last2=O'Brien|first2=D. F.|last3=You|first3=Y.|last4=Shoustikov|first4=A.|last5=Sibley|first5=S.|last6=Thompson|first6=M. E.|last7=Forrest|first7=S.R.|journal=Nature|volume=395|pages=151–154|issue=6698|bibcode = 1998Natur.395..151B |s2cid=4393960}}</ref><ref name=baldo2>{{cite journal|doi=10.1063/1.124258|title=Very high-efficiency green organic light-emitting devices based on electrophosphorescence|year=1999|last1=Baldo|first1=M. A.|last2=Lamansky|first2=S.|last3=Burrows|first3=P. E.|last4=Thompson|first4=M. E.|last5=Forrest|first5=S. R.|journal=Applied Physics Letters|volume=75|issue=1|page=4|bibcode = 1999ApPhL..75....4B }}</ref> with the internal quantum efficiencies of such devices approaching 100%.<ref>{{cite journal |last1=Adachi|first1=C.|last2=Baldo|first2=M. A.|last3=Thompson|first3=M. E.|last4=Forrest|first4=S. R.|year=2001|title=Nearly 100% internal phosphorescence efficiency in an organic light-emitting device|journal=Journal of Applied Physics|volume=90|page=5048|doi=10.1063/1.1409582 |issue=10|bibcode = 2001JAP....90.5048A }}</ref> PHOLEDs can be deposited using vacuum deposition through a shadow mask.<ref>{{cite book | url=https://books.google.com/books?id=KRT0DwAAQBAJ&dq=pholed+vacuum&pg=PA472 | title=Organic Electronics: Foundations to Applications | isbn=978-0-19-105356-6 | last1=Forrest | first1=Stephen R. | date=22 July 2020 | publisher=Oxford University Press }}</ref>
Typically, a polymer such as poly([[N-vinylcarbazole]]) is used as a host material to which an organometallic [[Coordination complex|complex]] is added as a dopant. [[Organoiridium compound|Iridium complexes]]<ref name=baldo2 /> such as Ir(mppy)<sub>3</sub><ref name=yang /> as of 2004 were a focus of research, although complexes based on other heavy metals such as platinum<ref name=baldo /> have also been used.
The heavy metal atom at the centre of these complexes exhibits strong spin-orbit coupling, facilitating [[intersystem crossing]] between [[Singlet state|singlet]] and [[Triplet state|triplet]] states. By using these phosphorescent materials, both singlet and triplet excitons will be able to decay radiatively, hence improving the internal quantum efficiency of the device compared to a standard OLED where only the singlet states will contribute to emission of light.
Applications of OLEDs in solid state lighting require the achievement of high brightness with good [[CIE 1931 color space|CIE coordinates]] (for white emission). The use of macromolecular species like polyhedral oligomeric silsesquioxanes (POSS) in conjunction with the use of phosphorescent species such as Ir for printed OLEDs have exhibited brightnesses as high as 10,000{{nbsp}}cd/m<sup>2</sup>.<ref>{{cite journal|doi=10.1039/b903531a|title=Electroluminescence from printed stellate polyhedral oligomeric silsesquioxanes|year=2009|last1=Singh|first1=Madhusudan|last2=Chae|first2=Hyun Sik|last3=Froehlich|first3=Jesse D.|last4=Kondou|first4=Takashi|last5=Li|first5=Sheng|last6=Mochizuki|first6=Amane|last7=Jabbour|first7=Ghassan E.|journal=Soft Matter|volume=5|page=3002|issue=16|bibcode = 2009SMat....5.3002S }}</ref>
== Device architectures ==
=== Structure ===
==== Bottom emission ====
[[File:Structures of BEOLED vs. TEOLED.png|thumb|a) Bottom-emitting and b) top-emitting OLED structures; c,d) Schematic diagrams based on bottom-emitting and top-emitting OLEDs with low and high contrast ratio, respectively.]]
The bottom-emission organic light-emitting diode (BE-OLED) is the architecture that was used in the early-stage [[AMOLED]] displays. It had a transparent anode fabricated on a glass substrate, and a shiny reflective cathode. Light is emitted from the transparent anode direction. To reflect all the light towards the anode direction, a relatively thick metal cathode such as aluminum is used. For the anode, high-transparency [[Indium tin oxide|indium tin oxide (ITO)]] was a typical choice to emit as much light as possible.<ref>{{Cite journal|last1=An|first1=Dong|last2=Liu|first2=Hongli|last3=Wang|first3=Shirong|last4=Li|first4=Xianggao|date=2019-04-15|title=Modification of ITO anodes with self-assembled monolayers for enhancing hole injection in OLEDs|url=http://aip.scitation.org/doi/10.1063/1.5086800|journal=Applied Physics Letters|language=en|volume=114|issue=15|page=153301|doi=10.1063/1.5086800|bibcode=2019ApPhL.114o3301A|s2cid=145936584|issn=0003-6951}}</ref> Organic thin-films, including the emissive layer that actually generates the light, are then sandwiched between the ITO anode and the reflective metal cathode. The downside of bottom emission structure is that the light has to travel through the pixel drive circuits such as the [[Thin-film transistor|thin film transistor (TFT)]] substrate, and the area from which light can be extracted is limited and the light emission efficiency is reduced.
==== Top emission ====
An alternative configuration is to switch the mode of emission. A reflective anode, and a transparent (or more often semi-transparent) cathode are used so that the light emits from the cathode side, and this configuration is called top-emission OLED (TE-OLED). Unlike BEOLEDs where the anode is made of transparent conductive ITO, this time the cathode needs to be transparent, and the ITO material is not an ideal choice for the cathode because of a damage issue due to the sputtering process.<ref>{{Cite journal|last1=Gil|first1=Tae Hyun|last2=May|first2=Christian|last3=Scholz|first3=Sebastian|last4=Franke|first4=Sebastian|last5=Toerker|first5=Michael|last6=Lakner|first6=Hubert|last7=Leo|first7=Karl|last8=Keller|first8=Stefan|date=February 2010|title=Origin of damages in OLED from Al top electrode deposition by DC magnetron sputtering|url=https://linkinghub.elsevier.com/retrieve/pii/S1566119909003413|journal=Organic Electronics|language=en|volume=11|issue=2|pages=322–331|doi=10.1016/j.orgel.2009.11.011}}</ref> Thus, a thin metal film such as pure Ag and the Mg:Ag alloy are used for the semi-transparent cathode due to their high [[transmittance]] and high [[Electrical resistivity and conductivity|conductivity]].<ref>{{Cite journal|last1=Im|first1=Jung Hyuk|last2=Kang|first2=Kyung-Tae|last3=Lee|first3=Sang Ho|last4=Hwang|first4=Jun Young|last5=Kang|first5=Heuiseok|last6=Cho|first6=Kwan Hyun|date=2016-06-01|title=Bulk-like Al/Ag bilayer film due to suppression of surface plasmon resonance for high transparent organic light emitting diodes|url=https://www.sciencedirect.com/science/article/pii/S1566119916300891|journal=Organic Electronics|language=en|volume=33|pages=116–120|doi=10.1016/j.orgel.2016.03.002|issn=1566-1199}}</ref> In contrast to the bottom emission, light is extracted from the opposite side in top emission without the need of passing through multiple drive circuit layers. Thus, the light generated can be extracted more efficiently.
=== Improvements ===
====Deuterium====
Using deuterium instead of hydrogen, in other words deuterated compounds, in red light , green light , blue light and white light OLED light emitting material layers and other layers nearby in OLED displays can improve their brightness by up to 30%. This is achieved by improving the current handling capacity, and lifespan of these materials.<ref>{{Cite web|url=https://newatlas.com/electronics/lg-display-oled-ex-deuterium/|title=LG Display swaps hydrogen for deuterium for brighter OLED screens|date=29 December 2021|website=New Atlas}}</ref><ref>{{Cite web|url=https://displaydaily.com/lg-display-enhances-oled-panels-with-expanded-deuterium-application/|title=LG Display Enhances OLED Panels with Expanded Deuterium Application|date=26 December 2023}}</ref><ref>{{Cite web|url=https://cen.acs.org/materials/electronic-materials/next-TV-contain-uncommon-isotopes/100/i9|title=How LG and DuPont worked together to bring deuterated compounds to next-generation TVs|website=Chemical & Engineering News}}</ref><ref>{{Cite web|url=https://www.oled-info.com/lg-display-aims-expand-use-deuterated-oled-compounds|title=LG Display aims to expand the use of deuterated OLED compounds &#124; OLED-Info|website=www.oled-info.com}}</ref>
====Micro Lens Array (MLA)====
Making indentations shaped like lenses on a transparent layer through which light passes from an OLED light emitting material, reduces the amount of scattered light and directs it forward, improving brightness.<ref>{{cite journal | doi=10.1080/15980316.2018.1531073 | title=Luminescence enhancement of OLED lighting panels using a microlens array film | date=2018 | last1=Han | first1=Jun-Han | last2=Moon | first2=Jaehyun | last3=Cho | first3=Doo-Hee | last4=Shin | first4=Jin-Wook | last5=Chu | first5=Hye Yong | last6=Lee | first6=Jeong-Ik | last7=Cho | first7=Nam Sung | last8=Lee | first8=Jonghee | journal=Journal of Information Display | volume=19 | issue=4 | pages=179–184 | doi-access=free }}</ref><ref>{{Cite web|url=https://patents.google.com/patent/KR20230102346A/en|title=Display apparatus}}</ref><ref>{{Cite web|url=https://www.oled-info.com/lg-display-could-adopt-microlens-array-its-oled-tv-panels-boost-brightness-and|title=LG Display could adopt a microLens array in its OLED TV panels to boost brightness and efficiency &#124; OLED-Info|website=www.oled-info.com}}</ref><ref>{{Cite journal|title=Performance evaluation of micro lens arrays: Improvement of light intensity and efficiency of white organic light emitting diodes|date=27 May 2022|journal=PLOS ONE|volume=17|issue=5|pages=e0269134|doi=10.1371/journal.pone.0269134|doi-access=free |last1=Adhikary |first1=Apurba |last2=Bhuiya |first2=Joy |last3=Murad |first3=Saydul Akbar |last4=Hossain |first4=Md. Bipul |last5=Uddin |first5=K. M. Aslam |last6=Faysal |first6=MD Estihad |last7=Rahaman |first7=Abidur |last8=Bairagi |first8=Anupam Kumar |pmid=35622833 |pmc=9140251 |bibcode=2022PLoSO..1769134A }}</ref><ref>{{Cite web|url=https://english.etnews.com/20230130200002|title=LGD, Micro Lens Array (MLA) Technology Applied for Gaming OLED as Well…Brightness 60%↑|date=30 January 2023|website=ETNEWS :: Korea IT News}}</ref>
==== Micro-cavity theory ====
[[File:Sony's Super Top Emission OLED.png|thumb|Sony's Super Top Emission OLED technology enhances the color purity of emitted lights.]]
When light waves meet while traveling along the same medium, [[wave interference]] occurs. This interference can be constructive or destructive. It is sometimes desirable for several waves of the same frequency to sum up into a wave with higher amplitudes.
Since both electrodes are reflective in TEOLED, light reflections can happen within the diode, and they cause more complex [[Wave interference|interferences]] than those in BEOLEDs. In addition to the two-beam interference, there exists a multi-resonance interference between two electrodes. Because the structure of TEOLEDs is similar to that of the [[Fabry–Pérot interferometer|Fabry-Perot resonator]] or [[Optical cavity|laser resonator]], which contains two parallel mirrors comparable to the two reflective electrodes),<ref>{{Cite journal|last1=Mizuno|first1=K.|last2=Ono|first2=S.|last3=Shibata|first3=Y.|date=August 1973|title=Two different mode interactions in an electron tube with a Fabry—Perot resonator—The Ledatron|url=https://ieeexplore.ieee.org/document/1477394|journal=IEEE Transactions on Electron Devices|volume=20|issue=8|pages=749–752|doi=10.1109/T-ED.1973.17737|bibcode=1973ITED...20..749M|issn=0018-9383}}</ref> this effect is especially strong in TEOLED. This two-beam interference and the Fabry-Perot interferences are the main factors in determining the output spectral intensity of OLED. This optical effect is called the "micro-cavity effect."
In the case of OLED, that means the cavity in a TEOLED could be especially designed to enhance the light output intensity and color purity with a narrow band of wavelengths, without consuming more power. In TEOLEDs, the microcavity effect commonly occurs, and when and how to restrain or make use of this effect is indispensable for device design. To match the conditions of constructive interference, different layer thicknesses are applied according to the resonance wavelength of that specific color. The thickness conditions are carefully designed and engineered according to the peak resonance emitting wavelengths of the blue light (460&nbsp;nm), green light (530&nbsp;nm), and red light (610&nbsp;nm) color LEDs. This technology greatly improves the light-emission efficiency of OLEDs, and are able to achieve a [[Wide Color Gamut|wider color gamut]] due to high color purity.
====Color filters====
In "[[#White + color filter method|white + color filter method]]", also known as WOLED,<ref>{{Cite web|url=https://www.rtings.com/tv/learn/qd-oled-vs-woled|title=QD-OLED vs. WOLED: What Type Of OLED Should You Buy?|website=RTINGS.com}}</ref> red, green, and blue emissions are obtained from the same white-light LEDs using different color filters.<ref>{{Cite journal |last1=Chen |first1=Shufen |last2=Deng |first2=Lingling |last3=Xie |first3=Jun |last4=Peng |first4=Ling |last5=Xie |first5=Linghai |last6=Fan |first6=Quli |last7=Huang |first7=Wei |date=2010-12-07 |title=Recent Developments in Top-Emitting Organic Light-Emitting Diodes |url=https://onlinelibrary.wiley.com/doi/10.1002/adma.201001167 |journal=Advanced Materials |language=en |volume=22 |issue=46 |pages=5227–5239 |doi=10.1002/adma.201001167 |pmid=20842657|bibcode=2010AdM....22.5227C |s2cid=23703980}}</ref> With this method, the OLED materials produce white light, which is then filtered to obtain the desired RGB colors. This method eliminated the need to deposit three different organic emissive materials, so only one kind of OLED material is used to produce white light. It also eliminated the [[#Color balance|uneven degradation]] rate of blue pixels vs. red and green pixels. Disadvantages of this method are low color purity and contrast. Also, the filters absorb most of the emitted light, requiring the background white light to be relatively strong to compensate for the drop in brightness, and thus the power consumption for such displays can be higher.
Color filters can also be implemented into bottom- and top-emission OLEDs. By adding the corresponding RGB color filters after the semi-transparent cathode, even purer wavelengths of light can be obtained. The use of a microcavity in top-emission OLEDs with color filters also contributes to an increase in the contrast ratio by reducing the reflection of incident ambient light.<ref>{{Cite journal |last1=Ishibashi |first1=Tadashi |last2=Yamada |first2=Jiro |last3=Hirano |first3=Takashi |last4=Iwase |first4=Yuichi |last5=Sato |first5=Yukio |last6=Nakagawa |first6=Ryo |last7=Sekiya |first7=Mitsunobu |last8=Sasaoka |first8=Tatsuya |last9=Urabe |first9=Tetsuo |date=2006-05-25 |title=Active Matrix Organic light Emitting Diode Display Based on "Super Top Emission" Technology |url=https://iopscience.iop.org/article/10.1143/JJAP.45.4392 |journal=Japanese Journal of Applied Physics |language=en |volume=45 |issue=5B |pages=4392–4395 |doi=10.1143/JJAP.45.4392 |bibcode=2006JaJAP..45.4392I |s2cid=121307571 |issn=0021-4922}}</ref> In a conventional panel, a circular polarizer was installed on the panel surface. While this was provided to prevent the reflection of ambient light, it also reduced the light output. By replacing this polarizing layer with color filters, the light intensity is not affected, and essentially all ambient reflected light can be cut, allowing a better contrast on the display panel. This potentially reduced the need for brighter pixels and can lower the power consumption.
=== Other architectures ===
====Transparent OLEDs====
Transparent OLEDs use transparent or semi-transparent contacts on both sides of the device to create displays that can be made to be both top and bottom emitting (transparent). TOLEDs can greatly improve contrast, making it much easier to view displays in bright sunlight.<ref>{{cite patent|country=US|number=5986401|title=High contrast transparent organic light emitting device display|inventor=Mark E. Thompson, Stephen R. Forrest, Paul Burrows|pubdate=1999-11-16}}</ref> This technology can be used in [[Head-up display]]s, smart windows or [[augmented reality]] applications.
====Graded heterojunction====
Graded heterojunction OLEDs gradually decrease the ratio of electron holes to electron transporting chemicals.<ref name="r2" /> This results in almost double the quantum efficiency of existing OLEDs.
====Stacked OLEDs====
Stacked OLEDs use a pixel architecture that stacks the red, green, and blue subpixels on top of one another instead of next to one another, leading to substantial increase in [[gamut]] and color depth,<ref>{{cite web|url=http://www.displaymate.com/LG_OLED_TV_ShootOut_1.htm |title=LG OLED TV Display Technology Shoot-Out |access-date=2017-03-01 |url-status=live |archive-url=https://web.archive.org/web/20170116045725/http://www.displaymate.com/LG_OLED_TV_ShootOut_1.htm |archive-date=2017-01-16 }}</ref> and greatly reducing pixel gap. Other display technologies with RGB (and RGBW) pixels mapped next to each other, tend to decrease potential resolution.
Tandem OLEDs are similar but have 2 layers of the same color stacked together. This improves the brightness of OLED displays.<ref>{{Cite web|url=https://www.androidauthority.com/what-is-tandem-oled-3464942/|title=What is tandem OLED and how does the display technology work?|date=26 July 2024|website=Android Authority}}</ref><ref>{{cite web | url=https://www.kipost.net/news/articleView.html?idxno=307043 | title=삼성디스플레이, 8.7세대 Oled 투자 규모 4.1조원 산정 | date=9 February 2023 }}</ref>
====Inverted OLED====
In contrast to a conventional OLED, in which the anode is placed on the substrate, an inverted OLED uses a bottom cathode that can be connected to the drain end of an n-channel TFT, especially for the low-cost [[amorphous silicon]] TFT backplane useful in the manufacturing of [[AMOLED]] displays.<ref>{{cite journal |doi=10.1063/1.2268923 |title=Highly efficient and stable inverted bottom-emission organic light emitting devices |year=2006 |last1=Chu |first1=Ta-Ya |last2=Chen |first2=Jenn-Fang |last3=Chen |first3=Szu-Yi |last4=Chen |first4=Chao-Jung |last5=Chen |first5=Chin H. |journal=Applied Physics Letters |volume=89 |page=053503 |issue=5 |bibcode=2006ApPhL..89e3503C }}</ref>
All OLED displays (passive and active matrix) use a driver IC, often mounted using the chip-on-glass (COG) technology with an [[anisotropic conductive film]].<ref>{{cite web | title=Advanced Display | website=Solomon Systech Limited | url=http://www.solomon-systech.com/en/product/advanced-display/oled-display-driver-ic/ | access-date=24 August 2020}}</ref>
== Color patterning technologies ==
=== Shadow mask patterning method ===
The most commonly used patterning method for organic light-emitting displays is shadow masking during film deposition,<ref>{{cite book|last1=Takatoshi|first1=Tsujimura|title=OLED Display Fundamentals and Applications|date=3 April 2017|publisher=John Wiley & Sons, Inc.|location=New York|isbn=978-1-119-18731-8|edition=2|url=https://www.wiley.com/en-jp/OLED+Display+Fundamentals+and+Applications,+2nd+Edition-p-9781119187318}}</ref> also called the "RGB side-by-side" method or "RGB pixelation" method. Metal sheets with multiple apertures made of low thermal expansion material, such as nickel alloy, are placed between the heated evaporation source and substrate, so that the organic or inorganic material from the evaporation source is masked off, or blocked by the sheet from reaching the substrate in most locations, so the materials are deposited only on the desired locations on the substrate, and the rest is deposited and remains on the sheet. Almost all small OLED displays for smartphones have been manufactured using this method.
Fine metal masks (FMMs) made by [[photochemical machining]], reminiscent of old CRT [[shadow mask]]s, are used in this process. The dot density of the mask will determine the pixel density of the finished display.<ref>{{Cite book|url=https://books.google.com/books?id=tCBwDQAAQBAJ&dq=Fine+metal+mask+oled&pg=PA141|title=OLED Displays and Lighting|first=Mitsuhiro|last=Koden|date=27 December 2016|publisher=John Wiley & Sons|isbn=978-1-119-04045-3 |via=Google Books}}</ref> Fine Hybrid Masks (FHMs) are lighter than FFMs, reducing bending caused by the mask's own weight, and are made using an electroforming process.<ref>{{cite web|url=https://www.oled-info.com/v-technology-start-producing-next-generation-oled-fine-metal-masks-acquires-oled-lighting-maker|title=V-Technology to start producing next-generation OLED fine metal masks, acquires OLED lighting maker Lumiotec|website=Oled-info.com}}</ref><ref>{{cite web|url=https://www.oled-a.org/v-technology-acquires-lumiotec-establishes-subsidiary-to-develop-oled-mask-and-deposition-technology-february-19-2018.html|title=V-technology Acquires Lumiotec; Establishes Subsidiary to Develop OLED Mask and Deposition Technology February 19, 2018|website=OLED Association}}</ref>
This method requires heating the electroluminescent materials at 300&nbsp;°C using a thermal method in a high vacuum of 10{{sup|−5}}{{nbsp}}Pa. An oxygen meter ensures that no oxygen enters the chamber as it could damage (through oxidation) the electroluminescent material, which is in powder form. The mask is aligned with the mother substrate before every use, and it is placed just below the substrate. The substrate and mask assembly are placed at the top of the deposition chamber.<ref>{{cite web|url=https://tokki.canon/eng/business/product/small.html|title=OLED: Small to Medium Volume Production System &#124; Products &#124; Products and Services|website=Canon Tokki Corporation}}</ref> Afterwards, the electrode layer is deposited, by subjecting silver and aluminum powder to 1000&nbsp;°C, using an electron beam.<ref name="auto1">{{cite web|url=https://tokki.canon/eng/business/el/technology.html|title=Canon Tokki's Distinctive Technology &#124; About OLED &#124; Products and Services|website=Canon Tokki Corporation}}</ref> Shadow masks allow for high pixel densities of up to {{convert|2250|dpi|dpcm|abbr=on}}. High pixel densities are
necessary for [[virtual reality headset]]s.<ref>{{cite web|url=https://www.oled-info.com/oled-developed-038um-shadow-mask-technology-enables-2250-ppi|title=OLEDON developed a 0.38um shadow mask technology that enables 2,250 PPI|website=Oled-info.com}}</ref>
=== White + color filter method (WOLED) ===
Although the shadow-mask patterning method is a mature technology used from the first OLED manufacturing, it causes many issues like [[dark spot]] formation due to mask-substrate contact or misalignment of the pattern due to the deformation of shadow mask. Such defect formation can be regarded as trivial when the display size is small, however it causes serious issues when a large display is manufactured, which brings significant production yield loss. To circumvent such issues, white emission devices with 4-sub-pixel color filters (white, red, green and blue) have been used for large televisions. In spite of the light absorption by the color filter, state-of-the-art OLED televisions can reproduce color very well, such as 100% [[NTSC]], and consume little power at the same time. This is done by using an emission spectrum with high human-eye sensitivity, special color filters with a low spectrum overlap, and performance tuning with color statistics into consideration.<ref>{{cite journal|title=LARGE-SIZE AMOLED TV BY "SCALABLE" TECHNOLOGIES (100% NTSC white + OLED technology theory)|journal=OLED Symposium 2009|date=1 October 2009|doi=10.13140/RG.2.2.23845.81122|url=https://www.researchgate.net/publication/321758497|author1=T Tsujimura}}</ref>
This approach is also called the "Color-by-white" method.
=== Other color patterning approaches ===
There are other types of emerging patterning technologies to increase the manufacturability of OLEDs.
Patternable organic light-emitting devices use a light or heat activated electroactive layer. A latent material ([[PEDOT-TMA]]) is included in this layer that, upon activation, becomes highly efficient as a hole injection layer. Using this process, light-emitting devices with arbitrary patterns can be prepared.<ref>{{cite journal|doi=10.1063/1.2746404|title=Photoactivated and patternable charge transport materials and their use in organic light-emitting devices|year=2007|last1=Liu|first1=Jie|last2=Lewis|first2=Larry N.|last3=Duggal|first3=Anil R.|journal=Applied Physics Letters|volume=90|page=233503|issue=23|bibcode = 2007ApPhL..90w3503L }}</ref>
Colour patterning can be accomplished by means of a laser, such as a radiation-induced sublimation transfer (RIST).<ref>{{cite journal|doi=10.1889/1.2036612|title=16.5L: Late-News-Paper: Non-Contact OLED Color Patterning by Radiation-Induced Sublimation Transfer (RIST)|year=2005|last1=Boroson|first1=Michael|last2=Tutt|first2=Lee|last3=Nguyen|first3=Kelvin|last4=Preuss|first4=Don|last5=Culver|first5=Myron|last6=Phelan|first6=Giana|journal=SID Symposium Digest of Technical Papers|volume=36|page=972|s2cid=135635712 }}</ref>
Organic vapour jet printing (OVJP) uses an inert carrier gas, such as [[argon]] or [[nitrogen]], to transport evaporated organic molecules (as in organic vapour phase deposition). The gas is expelled through a [[micrometre]]-sized nozzle or nozzle array close to the substrate as it is being translated. This allows printing arbitrary multilayer patterns without the use of solvents.
Like [[ink jet material deposition]], inkjet etching (IJE) deposits precise amounts of solvent onto a substrate designed to selectively dissolve the substrate material and induce a structure or pattern. Inkjet etching of polymer layers in OLED's can be used to increase the overall out-coupling efficiency. In OLEDs, light produced from the emissive layers of the OLED is partially transmitted out of the device and partially trapped inside the device by [[total internal reflection]] (TIR). This trapped light is wave-guided along the interior of the device until it reaches an edge where it is dissipated by either absorption or emission. Inkjet etching can be used to selectively alter the polymeric layers of OLED structures to decrease overall TIR and increase out-coupling efficiency of the OLED. Compared to a non-etched polymer layer, the structured polymer layer in the OLED structure from the IJE process helps to decrease the TIR of the OLED device. IJE solvents are commonly [[Organic compound|organic]] instead of water-based due to their non-acidic nature and ability to effectively dissolve materials at temperatures under the boiling point of water.<ref>{{Cite conference | doi = 10.1063/1.3455544| title = Inkjet Etching of Polymer Surfaces to Manufacture Microstructures for OLED Applications| conference = V INTERNATIONAL CONFERENCE ON TIMES OF POLYMERS (TOP) AND COMPOSITES. AIP Conference Proceedings| volume = 1255| pages = 104–106| series = AIP Conference Proceedings| year = 2010| last1 = Grimaldi | first1 = I. A.| last2 = De Girolamo Del Mauro | first2 = A.| last3 = Nenna | first3 = G.| last4 = Loffredo | first4 = F.| last5 = Minarini | first5 = C.| last6 = Villani | first6 = F.| last7 = d'Amore | first7 = A.| last8 = Acierno | first8 = D. | last9 = Grassia | first9 = L.
| bibcode = 2010AIPC.1255..104G}}</ref>
Transfer-printing is an emerging technology to assemble large numbers of parallel OLED and AMOLED devices efficiently.  It takes advantage of standard metal deposition, [[photolithography]], and etching to create alignment marks commonly on glass or other device substrates.  Thin polymer adhesive layers are applied to enhance resistance to particles and surface defects.  Microscale ICs are transfer-printed onto the adhesive surface and then baked to fully cure adhesive layers.  An additional photosensitive polymer layer is applied to the substrate to account for the topography caused by the printed ICs, reintroducing a flat surface.  Photolithography and etching removes some polymer layers to uncover conductive pads on the ICs. Afterwards, the anode layer is applied to the device backplane to form the bottom electrode.  OLED layers are applied to the anode layer with conventional [[vapor deposition]], and covered with a conductive metal electrode layer.  {{As of|2011}} transfer-printing was capable to print onto target substrates up to 500{{nbsp}}mm × 400{{nbsp}}mm.  This size limit needs to expand for transfer-printing to become a common process for the fabrication of large OLED/AMOLED displays.<ref>{{Cite journal | doi = 10.1109/TCPMT.2011.2128324| title = Transfer-Printed Microscale Integrated Circuits for High Performance Display Backplanes| journal = IEEE Transactions on Components, Packaging and Manufacturing Technology| volume = 1| issue = 12| pages = 1916–1922| year = 2011| last1 = Bower | first1 = C. A. | last2 = Menard | first2 = E. | last3 = Bonafede | first3 = S. | last4 = Hamer | first4 = J. W. | last5 = Cok | first5 = R. S. | s2cid = 22414052}}</ref>
Experimental OLED displays using conventional photolithography techniques instead of FMMs have been demonstrated, allowing for large substrate sizes (as it eliminates the need for a mask that needs to be as large as the substrate) and good yield control.<ref>{{cite web|url=https://www.oled-info.com/cpt-and-imec-demonstrate-1250-ppi-oled-patterned-using-photolithography-process|title=CPT and imec demonstrate an 1250 PPI OLED patterned using a photolithography process |website=Oled-info.com}}</ref> Visionox has announced the use of photolithography for depositing OLED emissive materials.<ref>{{Cite web|url=https://displaydaily.com/visionoxs-vip-advancing-amoled-display-with-photolithography-surpassing-traditional-fmm-limitations/|title=Visionox's ViP: Advancing AMOLED Display with Photolithography, Surpassing Traditional FMM Limitations|date=10 May 2023}}</ref>
== Thin-film transistor backplanes ==
For a high resolution display like a TV, a [[thin-film transistor]] (TFT) backplane is necessary to drive the pixels correctly. As of 2019, [[low-temperature polycrystalline silicon]] (LTPS){{nbsp}}– TFT is widely used for commercial [[AMOLED]] displays due to its superior current handling capacity over amorphous silicon (a-Si) TFTs.<ref>{{Cite book|url=https://books.google.com/books?id=4fX8DQAAQBAJ&dq=ltps+amoled&pg=PA28|title=Active-Matrix Organic Light- Emitting Display Technologies|first1=Shuming|last1=Chen|first2=Jianning|last2=Yu|first3=Yibin|last3=Jiang|first4=Rongsheng|last4=Chen|first5=Tsz Kin|last5=Ho|date=14 October 2015|publisher=Bentham Science Publishers|isbn=978-1-68108-120-5 |via=Google Books}}</ref> LTPS-TFT has variation of the performance in a display, so various compensation circuits have been reported.<ref name=r1>{{cite journal|doi=10.1889/1.1831876|title=24.4L: Late-News Paper: A 13.0-inch AM-OLED Display with Top Emitting Structure and Adaptive Current Mode Programmed Pixel Circuit (TAC)|year=2001|last1=Sasaoka|first1=Tatsuya|last2=Sekiya|first2=Mitsunobu|last3=Yumoto|first3=Akira|last4=Yamada|first4=Jiro|last5=Hirano|first5=Takashi|last6=Iwase|first6=Yuichi|last7=Yamada|first7=Takao|last8=Ishibashi|first8=Tadashi|last9=Mori|first9=Takao|last10=Asano|first10=Mitsuru|last11=Tamura|first11=Shinichiro|last12=Urabe|first12=Tetsuo|journal=SID Symposium Digest of Technical Papers|volume=32|page=384|s2cid=59976823 }}</ref> Due to the size limitation of the [[excimer laser]] used for LTPS, the [[AMOLED]] size was limited. To cope with the hurdle related to the panel size, amorphous-silicon/microcrystalline-silicon backplanes have been reported with large display prototype demonstrations.<ref>{{Cite journal | doi = 10.1889/1.1832193| title = 4.1: A 20-inch OLED Display Driven by Super-Amorphous-Silicon Technology| journal = SID Symposium Digest of Technical Papers| volume = 34| page = 6| year = 2003| last1 = Tsujimura | first1 = T. | last2 = Kobayashi | first2 = Y. | last3 = Murayama | first3 = K. | last4 = Tanaka | first4 = A. | last5 = Morooka | first5 = M. | last6 = Fukumoto | first6 = E. | last7 = Fujimoto | first7 = H. | last8 = Sekine | first8 = J. | last9 = Kanoh | first9 = K. | last10 = Takeda | first10 = K. | last11 = Miwa | first11 = K. | last12 = Asano | first12 = M. | last13 = Ikeda | first13 = N. | last14 = Kohara | first14 = S. | last15 = Ono | first15 = S. | last16 = Chung | first16 = C. T. | last17 = Chen | first17 = R. M. | last18 = Chung | first18 = J. W. | last19 = Huang | first19 = C. W. | last20 = Guo | first20 = H. R. | last21 = Yang | first21 = C. C. | last22 = Hsu | first22 = C. C. | last23 = Huang | first23 = H. J. | last24 = Riess | first24 = W. | last25 = Riel | first25 = H. |author25-link=Heike Riel| last26 = Karg | first26 = S. | last27 = Beierlein | first27 = T. | last28 = Gundlach | first28 = D. | last29 = Alvarado | first29 = S. | last30 = Rost | first30 = C. | s2cid = 135831267| display-authors = 29}}</ref> An [[indium gallium zinc oxide]] (IGZO) backplane can also be used. Large OLED displays usually use AOS (amporphous oxide semiconductor) TFT transistors instead, also called oxide TFTs<ref>https://www.corning.com/media/worldwide/global/documents/Markets_Display_Wager%20Information%20Display%202020.pdf</ref> and these are usually based on IGZO.<ref>{{cite book | url=https://books.google.com/books?id=-yaJEAAAQBAJ&dq=ltpo+amoled&pg=PA116 | isbn=978-1-119-86958-0 | title=Advances in Semiconductor Technologies: Selected Topics Beyond Conventional CMOS | date=11 October 2022 | publisher=John Wiley & Sons }}</ref>
Many AMOLED displays use [[Low-temperature polycrystalline silicon#LTPO|LTPO]] TFT transistors. These transistors offer stability at low refresh rates, and variable refresh rates, which allows for power saving displays that do not show visual artifacts.<ref>{{cite journal | url=https://sid.onlinelibrary.wiley.com/doi/abs/10.1002/sdtp.12978 | doi=10.1002/sdtp.12978 | title=39-3: ''Invited Paper:'' LTPO TFT Technology for AMOLEDs<sup>†</sup> | date=2019 | last1=Chang | first1=Ting-Kuo | last2=Lin | first2=Chin-Wei | last3=Chang | first3=Shihchang | journal=Sid Symposium Digest of Technical Papers | volume=50 | pages=545–548 | s2cid=191192447 }}</ref><ref>{{cite journal | url=https://sid.onlinelibrary.wiley.com/doi/10.1002/sdtp.13595 | doi=10.1002/sdtp.13595 | title=P-1.1: A New Compensation Pixel Circuit with LTPO TFTS | date=2019 | last1=Chen | first1=Qian | last2=Su | first2=Yue | last3=Shi | first3=Xuewen | last4=Liu | first4=Dongyang | last5=Gong | first5=Yuxin | last6=Duan | first6=Xinlv | last7=Ji | first7=Hansai | last8=Geng | first8=Di | last9=Li | first9=Ling | last10=Liu | first10=Ming | journal=Sid Symposium Digest of Technical Papers | volume=50 | pages=638–639 | s2cid=210522411 }}</ref><ref>{{cite journal | url=https://sid.onlinelibrary.wiley.com/doi/abs/10.1002/sdtp.13876 | doi=10.1002/sdtp.13876 | title=24-3: Complementary LTPO Technology, Pixel Circuits and Integrated Gate Drivers for AMOLED Displays Supporting Variable Refresh Rates | date=2020 | last1=Luo | first1=Haojun | last2=Wang | first2=Shaowen | last3=Kang | first3=Jiahao | last4=Wang | first4=Yu-Min | last5=Zhao | first5=Jigang | last6=Tsong | first6=Tina | last7=Lu | first7=Ping | last8=Gupta | first8=Amit | last9=Hu | first9=Wenbing | last10=Wu | first10=Huanda | last11=Zhang | first11=Shengwu | last12=Kim | first12=Jiha | last13=Chiu | first13=Chang Ming | last14=Lee | first14=Bong-Geum | last15=Yuan | first15=Ze | last16=Yu | first16=Xiaojun | journal=Sid Symposium Digest of Technical Papers | volume=51 | pages=351–354 | s2cid=225488161 }}</ref>
== Advantages ==
{{further|Comparison of CRT, LCD, plasma, and OLED displays}}
The different manufacturing process of OLEDs has several advantages over [[flat panel display]]s made with LCD technology.
; Lower cost in the future: OLEDs can be printed onto any suitable [[substrate (printing)|substrate]] by an inkjet printer or even by screen printing,<ref>{{cite journal|doi=10.1002/1521-4095(200009)12:17<1249::AID-ADMA1249>3.0.CO;2-Y|title=Application of Screen Printing in the Fabrication of Organic Light-Emitting Devices|year=2000|last1=Pardo|first1=Dino A.|last2=Jabbour|first2=G. E.|last3=Peyghambarian|first3=N.|journal=Advanced Materials|volume=12|pages=1249–1252|issue=17|bibcode=2000AdM....12.1249P }}</ref> theoretically making them cheaper to produce than LCD or [[plasma display]]s. However, fabrication of the OLED substrate as of 2018 is costlier than that for TFT LCDs.<ref>{{cite web | url=https://appleinsider.com/articles/18/04/04/explaining-microled-versus-tft-and-oled-display-technologies-and-why-apple-is-interested-for-a-future-iphone-or-apple-watch | date=2018 | title=MicroLED vs. TFT and OLED: Why Apple is interested in new display tech for future iPhone or Apple Watch | author=Malcolm Owen}}</ref> Roll-to-roll vapor-deposition methods for organic devices do allow mass production of thousands of devices per minute for minimal cost; however, this technique also induces problems: devices with multiple layers can be challenging to make because of [[Printing registration|registration]] — lining up the different printed layers to the required degree of accuracy.
; Lightweight and flexible plastic substrates: OLED displays can be fabricated on flexible plastic substrates, leading to the possible fabrication of [[flexible organic light-emitting diode]]s for other new applications, such as [[rollable display|roll-up displays]] embedded in fabrics or clothing. If a substrate like [[polyethylene terephthalate]] (PET)<ref>{{cite journal|doi=10.1038/357477a0|title=Flexible light-emitting diodes made from soluble conducting polymers|year=1992|last1=Gustafsson|first1=G.|last2=Cao|first2=Y.|last3=Treacy|first3=G. M.|last4=Klavetter|first4=F.|last5=Colaneri|first5=N.|last6=Heeger|first6=A. J.|journal=Nature|volume=357|pages=477–479|issue=6378|bibcode=1992Natur.357..477G|s2cid=4366944}}</ref> can be used, the displays may be produced inexpensively.  Furthermore, plastic substrates are shatter-resistant, unlike the glass displays used in LCD devices. Flexible OLED displays are made on polyamide plastic films which are bonded to glass panels during production. Once the OLED display is encapsulated, a Laser is used to separate the plastic from the glass in a Laser Lift-Off (LLO) process.<ref>{{Cite web|url=https://displaydaily.com/omniply-stick-and-peel-process-a-substitute-for-llo/|title=Omniply Stick and Peel Process: A Substitute for LLO|date=31 October 2022}}</ref>
; Power efficiency: LCDs filter the light emitted from a [[backlight]], allowing a small fraction of light through. Thus, they cannot show true black. However, an inactive OLED element does not produce light or consume power, allowing true blacks.<ref>{{cite web|url=http://www.oled-research.com/oleds/oleds-lcd.html |title=Comparison of OLED and LCD |publisher=Fraunhofer IAP: OLED Research |date=2008-11-18 |access-date=2010-01-25 |url-status=dead |archive-url=https://web.archive.org/web/20100204030227/http://www.oled-research.com/oleds/oleds-lcd.html |archive-date=4 February 2010 }}</ref> Removing the backlight also makes OLEDs lighter because some substrates are not needed.
; Response time: OLEDs also have a much faster [[pixel response time|response time]] than an LCD. Using response time compensation technologies, the fastest modern LCDs can reach response times as low as [[Liquid crystal display#Specifications|1{{nbsp}}ms]] for their fastest color transition, and are capable of [[refresh rate|refresh frequencies]] as high as 240{{nbsp}}Hz. According to [[LG Corporation|LG]], OLED response times are up to 1,000 times faster than LCD,<ref>{{cite web|url=http://www.oled-info.com/lg-55em9700 |date=2013-01-02 |title=LG 55EM9700 |access-date=2015-01-14 |url-status=live |archive-url=https://web.archive.org/web/20150115001508/http://www.oled-info.com/lg-55em9700 |archive-date=2015-01-15 }}</ref> putting conservative estimates at under 10{{nbsp}}μs (0.01{{nbsp}}ms), which could theoretically accommodate refresh frequencies approaching 100{{nbsp}}kHz (100,000{{nbsp}}Hz). Due to their extremely fast response time, OLED displays can also be easily designed to be strobed, creating an effect similar to CRT flicker in order to avoid the [[sample-and-hold]] behavior seen on both LCDs and some OLED displays, which creates the perception of [[motion blur]].<ref>{{cite web|url=http://www.blurbusters.com/faq/oled-motion-blur/ |title=Why Do Some OLEDs Have Motion Blur? |publisher=Blur Busters Blog (based on Microsoft Research work) |date=2013-04-15 |access-date=2013-04-18 |url-status=live |archive-url=https://web.archive.org/web/20130403030530/http://www.blurbusters.com/faq/oled-motion-blur/ |archive-date=2013-04-03 }}</ref>
; High dynamic range support: Because OLEDs can turn off individual pixels showing true black, the contrast ratio of an OLED display can be very large, which allows for representation of [[high dynamic range]] (HDR) images and video at high quality. Data must be encoded with a HDR format to display in HDR, and HDR format support varies by OLED display. Maximum (peak) brightness also varies by OLED display, which impacts the dynamic range that can be represented.
== Disadvantages ==
[[File:Light Emitting Polymer display partially failed.jpg|thumb|Light-emitting polymer (LEP) display showing partial failure]]
[[File:Oled display alterung.jpg|thumb|An old OLED display showing wear]]
===Lifespan===
The biggest technical problem for OLEDs is the limited lifetime of the organic materials. One 2008 technical report on an OLED TV panel found that after 1,000{{nbsp}}hours, the blue luminance degraded by 12%, the red by 7% and the green by 8%.<ref>"OLED TV estimated lifespan shorter then expected". HDTV Info Europe. Hdtvinfo.eu (2008-05-08).</ref> In particular, blue OLEDs at that time had a lifetime of around 14,000{{nbsp}}hours to half original brightness (five years at eight hours per day) when used for flat-panel displays. This is lower than the typical lifetime of LCD, LED or [[plasma display|PDP]] technology; each rated for about 25,000–40,000{{nbsp}}hours to half brightness, depending on manufacturer and model. One major challenge for OLED displays is the formation of dark spots due to the ingress of oxygen and moisture, which degrades the organic material over time whether or not the display is powered.<ref>https://www.webcitation.org/5vzeAMFjZ?url=http://ec1.images-amazon.com/media/i3d/01/A/man-migrate/MANUAL000020267.pdf</ref><ref>{{Cite web |url=http://ap.viewsonic.com/za/product_pdfs/lcd/19/E-VX1932wm-LED.pdf |title=Archived copy |access-date=9 April 2011 |archive-date=1 June 2023 |archive-url=https://web.archive.org/web/20230601120834/http://ap.viewsonic.com/za/product_pdfs/lcd/19/E-VX1932wm-LED.pdf |url-status=dead }}</ref><ref>{{cite web |last1=Phatak |first1=Radhika |title=Dependence of dark spot growth on cathode/organic interfacial adhesion in Organic Light Emitting Devices |url=https://uwspace.uwaterloo.ca/bitstream/handle/10012/6179/Phatak_Radhika.pdf |website=UWSpaceuwaterloo.ca |publisher=University of Waterloo |access-date=22 April 2019 |page=21 |language=en}}</ref> In 2016, LG Electronics reported an expected lifetime of 100,000 hours, up from 36,000 hours in 2013.<ref>{{cite web|url=https://www.flatpanelshd.com/news.php?id=1465304750&subaction=showfull|title=LG: OLED TV lifespan is now 100,000 hours - FlatpanelsHD|website=Flatpanelshd.com}}</ref>  A US Department of Energy paper shows that the expected lifespans of OLED lighting products goes down with increasing brightness, with an expected lifespan of 40,000 hours at 25% brightness, or 10,000 hours at 100% brightness.<ref>{{cite web|url=https://www.techhive.com/article/3239350/will-hdr-kill-your-oled-tv.html|title=Will HDR kill your OLED TV?|date=27 June 2018|website=TechHive.com}}</ref><ref>{{cite web |url=https://energy.gov/sites/prod/files/2016/06/f33/ssl_oled-products_2016.pdf |title=Archived copy |website=Energy.gov |access-date=15 January 2022 |archive-url=https://web.archive.org/web/20170226114613/https://energy.gov/sites/prod/files/2016/06/f33/ssl_oled-products_2016.pdf |archive-date=26 February 2017 |url-status=dead}}</ref> Compare to [[LCD]]s, OLEDs may more easy to appear [[screen burn-in]] and/or brightness degradation.
====Degradation====
{{Technical|subsection|date=April 2019}}
Degradation occurs because of the accumulation of [[Carrier generation and recombination|nonradiative recombination]] centers and luminescence quenchers in the emissive zone. It is said that the chemical breakdown in the semiconductors occurs in four steps:
# recombination{{efn|The energy absorbed by a material is released in the form of photons. Generally these photons contain the same or less energy than those initially absorbed. This effect is how LEDs create light.}} of charge carriers through the absorption of [[Ultraviolet|UV light]]
# [[Homolysis (chemistry)|homolytic dissociation]]
# subsequent radical addition reactions that form {{pi}} radicals
# disproportionation between two radicals resulting in hydrogen-atom transfer reactions<ref>{{cite journal|last=Kondakov|first=D|author2=Lenhart, W. |author3=Nochols, W. |title=Operational degradation of organic light-emitting diodes: Mechanism and identification of chemical products|journal=Journal of Applied Physics|year=2007|volume=101|issue=2|pages=024512–024512–7|doi=10.1063/1.2430922|bibcode = 2007JAP...101b4512K }}</ref>
In 2007, experimental OLEDs were created which can sustain 400{{nbsp}}cd/m<sup>2</sup> of [[luminance]] for over 198,000{{nbsp}}hours for green OLEDs and 62,000{{nbsp}}hours for blue OLEDs.<ref>[[Cambridge Display Technology]], [http://www.cdtltd.co.uk/technology/status/ Cambridge Display Technology and Sumation Announce Strong Lifetime Improvements to P-OLED (Polymer OLED) Material; Blue P-OLED Materials Hit 10,000 Hour Lifetime Milestone at 1,000 cd/sq.m], 26 March 2007. Retrieved 11 January 2011. {{webarchive |url=https://web.archive.org/web/20101226083113/http://www.cdtltd.co.uk/technology/status/ |date=26 December 2010 }}</ref> In 2012, OLED lifetime to half of the initial brightness was improved to 900,000{{nbsp}}hours for red, 1,450,000{{nbsp}}hours for yellow and 400,000{{nbsp}}hours for green at an initial [[luminance]] of 1,000{{nbsp}}cd/m<sup>2</sup>.<ref>{{cite web|url=https://www.oled-info.com/oled-lifetime|title=OLED Lifetime: introduction and market status {{!}} OLED-Info|website=Oled-info.com|access-date=2019-04-18}}</ref> Proper encapsulation is critical for prolonging an OLED display's lifetime, as the OLED light emitting electroluminescent materials are sensitive to oxygen and moisture. When exposed to moisture or oxygen, the electroluminescent materials in OLEDs degrade as they oxidize, generating black spots and reducing or shrinking the area that emits light, reducing light output. This reduction can occur in a pixel by pixel basis. This can also lead to delamination of the electrode layer, eventually leading to complete panel failure.
Degradation occurs three orders of magnitude faster when exposed to moisture than when exposed to oxygen. Encapsulation can be performed by applying an epoxy adhesive with dessicant,<ref name="auto">{{cite web|url=https://www.saesgetters.com/oled-encapsulation|title=OLED encapsulation|website=Saesgetters.com}}</ref> by laminating a glass sheet with epoxy glue and dessicant<ref>{{cite web|url=https://tokki.canon/eng/business/file/el_catalog_en.pdf |title=OLED Production Systems : ELVESS|website=Tokki.canon|access-date=5 March 2022}}</ref> followed by vacuum degassing, or by using Thin-Film Encapsulation (TFE),<ref>{{Cite book|chapter-url=https://link.springer.com/referenceworkentry/10.1007/978-4-431-55761-6_26-1|title=Handbook of Organic Light-Emitting Diodes|first1=Robert Jan|last1=Visser|first2=Lorenza|last2=Moro|first3=Xi|last3=Chu|first4=Jerry R.|last4=Chen|first5=Peter|last5=van de Weijer|first6=Hylke B.|last6=Akkerman|first7=Samuel|last7=Graham|first8=Mikko|last8=Söderlund|first9=Alberto|last9=Perrotta|first10=Maria Adriana|last10=Creatore|chapter=Thin Film Encapsulation |editor-first1=Chihaya|editor-last1=Adachi|editor-first2=Reiji|editor-last2=Hattori|editor-first3=Hironori|editor-last3=Kaji|editor-first4=Takatoshi|editor-last4=Tsujimura|date=21 September 2018|publisher=Springer Japan|pages=1–51|via=Springer Link|doi=10.1007/978-4-431-55761-6_26-1|isbn=978-4-431-55761-6 }}</ref> which is a multi-layer coating of alternating organic and inorganic layers. The organic layers are applied using inkjet printing, and the inorganic layers are applied using [[Atomic Layer Deposition]] (ALD). The encapsulation process is carried out under a nitrogen environment, using UV-curable [[Liquid optically clear adhesive|LOCA]] glue and the electroluminescent and electrode material deposition processes are carried out under a high vacuum. The encapsulation and material deposition processes are carried out by a single machine, after the [[Thin-film transistor]]s have been applied. The transistors are applied in a process that is the same for LCDs. The electroluminescent materials can also be applied using inkjet printing.<ref>{{cite web|url=https://www.idtechex.com/en/research-article/printing-oled-displays-has-its-time-finally-come/16673|title=Printing OLED displays: has its time finally come?|website=Idtechex.com|date=27 February 2019}}</ref><ref>{{cite web|url=https://www.oled-info.com/oled-inkjet-printing|title=OLED ink jet printing: introduction and market status |website=Oled-info.com}}</ref><ref>{{cite web|url=https://www.radiantvisionsystems.com/blog/inkjet-printing-answer-oled-production-challenges|title=Is Inkjet Printing the Answer to OLED Production Challenges?|date=29 July 2019|website=Radiant Vision Systems}}</ref><ref name="auto1"/><ref name="auto2">{{cite web|url=https://www.oled-info.com/oled-encapsulation|title=OLED Encapsulation: introduction and market status &#124; OLED-Info|website=Oled-info.com}}</ref><ref name="auto"/><ref>{{cite web|url=https://www.ifixit.com/News/galaxy-fold-failure-causes|title=Here's Why We Think Galaxy Folds Are Failing|date=23 April 2019|website=iFixit.com}}</ref>
===Color balance===
The OLED material used to produce blue light degrades much more rapidly than the materials used to produce other colors; in other words, blue light output will decrease relative to the other colors of light. This variation in the differential color output will change the [[white balance|color balance]] of the display, and is much more noticeable than a uniform decrease in overall luminance.<ref>{{cite web|url=http://digidelve.com/tech/ageless-oled/ |archive-url=https://web.archive.org/web/20070908033812/http://www.digidelve.com/tech/ageless-oled/ |url-status=dead |archive-date=2007-09-08 |title=Ageless OLED |access-date=2009-11-16 }}</ref> This can be avoided partially by adjusting the color balance, but this may require advanced control circuits and input from a knowledgeable user. More commonly, though, manufacturers optimize the size of the R, G and B subpixels to reduce the current density through the subpixel in order to equalize lifetime at full luminance.  For example, a blue subpixel may be 75% larger than the green subpixel. The red subpixel may be 10% larger than the green.
===Efficiency of blue OLEDs===
{{Technical|subsection|date=April 2019}}
Improvements to the efficiency and lifetime of blue OLEDs is vital to the success of OLEDs as replacements for LCD technology. Considerable research has been invested in developing blue OLEDs with high [[external quantum efficiency]], as well as a deeper blue color.<ref>{{cite journal|last1=Fallahi |first1=Afsoon |last2=Afshar Taromi |first2=Faramarz |last3=Mohebbi |first3=Alireza |last4=D. Yuen |first4=Jonathan |last5=Shahinpoor |first5=Mohsen |title=A novel ambipolar polymer: from organic thin-film transistors to enhanced air-stable blue light emitting diodes |journal=Journal of Materials Chemistry C |date=2014 |volume=2 |issue=32 |page=6491 |doi=10.1039/c4tc00684d }}</ref><ref>{{cite journal|doi=10.1039/b501819f|title=High Tg blue emitting materials for electroluminescent devices|year=2005|last1=Shen|first1=Jiun Yi|last2=Lee|first2=Chung Ying|last3=Huang|first3=Tai-Hsiang|last4=Lin|first4=Jiann T.|last5=Tao|first5=Yu-Tai|last6=Chien|first6=Chin-Hsiung|last7=Tsai|first7=Chiitang|journal=Journal of Materials Chemistry|volume=15|page=2455|issue=25}}</ref><ref>{{cite journal|doi=10.1016/j.synthmet.2010.03.020|title=A highly efficient deep blue fluorescent OLED based on diphenylaminofluorenylstyrene-containing emitting materials|year=2010|last1=Kim|first1=Seul Ong|last2=Lee|pages=1259–1265|first2=Kum Hee|last3=Kim|first3=Gu Young|volume=160|last4=Seo|first4=Ji Hoon|last5=Kim|first5=Young Kwan|last6=Yoon|first6=Seung Soo|journal=Synthetic Metals|issue=11–12}}</ref>
Since 2012, research focuses on organic materials exhibiting [[TADF|thermally activated delayed fluorescence]] (TADF), discovered at [[Kyushu University#Center for Organic Photonics and Electronics Research|Kyushu University OPERA]] and [[University of California, Santa Barbara|UC Santa Barbara CPOS]]. TADF would allow stable and high-efficiency solution processable (meaning that the organic materials are layered in solutions producing thinner layers) blue emitters, with [[internal quantum efficiency|internal quantum efficiencies]] reaching 100%.<ref>Wong M. Y., Hedley G. J., Xie G., Kölln L. S, Samuel I. D. W., Pertegaś A., Bolink H. J., Mosman-Colman, E., "Light-emitting electrochemical cells and solution-processed organic light-emitting diodes using small molecule organic thermally activated delayed fluorescence emitters", ''[[Chemistry of Materials]]'', vol. 27, no. 19, pp.{{nbsp}}6535–6542, {{doi|10.1021/acs.chemmater.5b03245}}</ref> Early in 2017,<ref name="sciencedirect.com"/> TADF materials based on oxygen-based fully bridged boron-type electron accepttors had achieved huge breakthrough in their proprities. The external quantum efficiency of TADF-OLED for blue and green light had achieved 38%, with thin full-width half-maximum and high color purity. In 2022, Han et al.<ref>{{Cite journal |last1=Han |first1=Jianmei |last2=Huang |first2=Zhongyan |last3=Miao |first3=Jingsheng |last4=Qiu |first4=Yuntao |last5=Xie |first5=Ziyang |last6=Yang |first6=Chuluo |date=2022 |title=Narrowband blue emission with insensitivity to the doping concentration from an oxygen-bridged triarylboron-based TADF emitter: nondoped OLEDs with a high external quantum efficiency up to 21.4% |url=http://xlink.rsc.org/?DOI=D2SC00329E |journal=Chemical Science |language=en |volume=13 |issue=12 |pages=3402–3408 |doi=10.1039/D2SC00329E |issn=2041-6520 |pmc=8943898 |pmid=35432872}}</ref> synthesized a new D-A type luminescent material, TDBA-Cz, and used the m-AC-DBNA synthesized by Meng et al. as a control to investigate the effect of the substitution site of the carbazole unit as an electron donor on the oxygen-bridged triphenylboron electron acceptor unit on the photophysical properties of the overall molecule. It was found that the introduction of two carbazole units into the same benzene ring of the oxygen-bridged triphenylboron electron acceptor unit could effectively suppress the conformational relaxation of the molecule during the radiative transition, resulting in narrow bandwidth blue light emission. In addition, TDBA-Cz is the first reported blue material to achieve both a FWHM down to 45&nbsp;nm and a maximum EQE of 21.4% in a non-doped TADF-OLED.
Blue TADF emitters are expected to market by 2020<ref>{{cite web | url=https://www.oled-info.com/kyulux-signs-jda-agreements-both-sdc-and-lgd-aims-have-commercial-ready-tadfhf-emitters-ready-mid | title=Kyulux signs JDA agreements with both SDC and LGD - aims to have commercial ready TADF/HF emitters ready by mid 2019 &#124; OLED-Info}}</ref><ref>{{cite web | url=https://www.oled-info.com/cynora-present-its-latest-blue-tadf-emitter-oleds-world-summit-conference | title=Cynora to present its latest blue TADF emitter at the OLEDs World Summit conference &#124; OLED-Info}}</ref> and would be used for [[#White + color filter method|WOLED]] displays with phosphorescent color filters, as well as blue OLED displays with ink-printed [[quantum dot display#QDCF|QD color filters]].
===Water damage===
Water can instantly damage the organic materials of the displays. Therefore, improved sealing processes are important for practical manufacturing. Water damage especially may limit the longevity of more flexible displays.<ref>{{cite web|url=http://www.gtresearchnews.gatech.edu/newsrelease/oled-encapsulation.htm|archive-url=https://web.archive.org/web/20080708202810/http://gtresearchnews.gatech.edu/newsrelease/oled-encapsulation.htm|url-status=dead|archive-date=2008-07-08|title=OLED Sealing Process Reduces Water Intrusion and Increases Lifetime|website=Georgia Tech Research News|date=2008-04-23}}</ref>
===Outdoor performance===
As an emissive display technology, OLEDs rely completely upon converting electricity to light, unlike most LCDs which are to some extent reflective. [[Electronic paper|E-paper]] leads the way in efficiency with ~ 33% ambient light reflectivity, enabling the display to be used without any internal light source. The metallic cathode in an OLED acts as a mirror, with reflectance approaching 80%, leading to poor readability in bright ambient light such as outdoors. However, with the proper application of a [[circular polarizer]] and [[antireflective coating]]s, the diffuse reflectance can be reduced to less than 0.1%.  With 10,000 [[foot-candle|fc]] incident illumination (typical test condition for simulating outdoor illumination), that yields an approximate [[photopic contrast]] of 5:1. Advances in OLED technologies, however, enable OLEDs to become actually better than LCDs in bright sunlight. The [[AMOLED]] display in the [[Galaxy S5]], for example, was found to outperform all LCD displays on the market in terms of power usage, brightness and reflectance.<ref>{{cite web|url=https://www.oled-info.com/displaymate-gs5-display-best-mobile-display-ever-outperforming-all-previous-oled-and-lcd-panels|archive-url=https://web.archive.org/web/20140403052815/http://www.oled-info.com/displaymate-gs5-display-best-mobile-display-ever-outperforming-all-previous-oled-and-lcd-panels|url-status=dead|title=DisplayMate: the GS5 display is the best mobile display ever, outperforming all previous OLED and LCD panels |archive-date=3 April 2014|website=Oled-info.com}}</ref>
===Power consumption===
While an OLED will consume around 40% of the power of an LCD displaying an image that is primarily black, for the majority of images it will consume 60–80% of the power of an LCD. However, an OLED can use more than 300% power to display an image with a white background, such as a document or web site.<ref>Stokes, Jon. (2009-08-11) [https://arstechnica.com/gadgets/news/2009/08/this-september-oled-no-longer-three-to-five-years-away.ars This September, OLED no longer "three to five years away"] {{webarchive|url=https://web.archive.org/web/20120125223142/http://arstechnica.com/gadgets/news/2009/08/this-september-oled-no-longer-three-to-five-years-away.ars |date=2012-01-25 }}. Arstechnica.com. Retrieved 2011-10-04.</ref> This can lead to reduced battery life in mobile devices when white backgrounds are used.
=== Screen flicker ===
Many OLEDs use [[pulse width modulation]] to display colour/brightness gradations. For example, a pixel instructed to display gray will flicker on and off rapidly, creating a subtle strobe effect.<ref name=pwm>{{cite web|url=https://www.oled-info.com/pulse-width-modulation-pwm-oled-displays|title=Pulse-width modulation (PWM) in OLED displays|date=14 January 2018|website=OLED-Info|first1=Ron|last1=Mertens|first2=Marat|last2=Tanalin|access-date=12 August 2023}}</ref> The alternative way to decrease brightness would be to decrease power to the display, which would eliminate screen flicker to the detriment of [[colour balance]], which deteriorates as brightness decreases. However, use of PWM gradations may be more harmful for eye health.<ref>{{cite web |date=20 April 2022 |title=Is AMOLED display bad for your eyes? All you need to know about flicker and PWM - Tech Longreads |url=https://techlongreads.com/smartphones/amoled-pwm-explained/ |url-status=dead |archive-url=https://web.archive.org/web/20240317081640/https://techlongreads.com/smartphones/amoled-pwm-explained/ |archive-date=March 17, 2024}}</ref>
==Manufacturers and commercial uses==
[[File:Nexus one screen microscope.jpg|thumb|Magnified image of the [[AMOLED]] screen on the Google [[Nexus One]] smartphone using the [[PenTile RGBG|RGBG]] system of the [[PenTile Matrix Family]]]]
[[File:OLEDScreen.jpg|thumb|A 3.8{{nbsp}}cm (1.5{{nbsp}}in) OLED display from a Creative [[ZEN V]] media player]]
[[File:Aquis Plaza OLED Kunstwerk.jpg|thumb|OLED lighting in a [[shopping mall]] in [[Aachen]], [[Germany]]]]
Almost all OLED manufacturers rely on material deposition equipment that is only made by a handful of companies,<ref>{{cite web|url=https://www.oled-info.com/tags/manufacturing_equipment|title=Manufacturing equipment|website=Oled-info.com}}</ref> the most notable one being [[Canon Tokki]], a unit of [[Canon Inc.]] although Ulvac and Sunic System are also notable.<ref>{{cite web | url=https://english.etnews.com/20210817200001 | title=Conversion to '8th generation' small and medium sized OLED... Visible investment plans of Samsung and LG within this year | date=17 August 2021 }}</ref><ref>https://thelec.net/news/articleView.html?idxno=4247&replyAll=&reply_sc_order_by=I</ref>  Canon Tokki is reported to have a near-monopoly of the giant OLED-manufacturing vacuum machines, notable for their {{convert|100|m|adj=on}} size.<ref>{{Cite news|url=https://www.japantimes.co.jp/news/2017/04/24/business/tech/ahead-next-iphone-idemitsu-kosan-leads-way-developing-oled-screen/|title=Ahead of next iPhone, Idemitsu Kosan leads way after developing OLED screen|last1=Alpeyev|first1=Pavel|date=2017-04-24|work=The Japan Times Online|access-date=2018-05-31|last2=Taniguchi|first2=Takako|language=en-US|issn=0447-5763}}</ref> [[Apple Inc.|Apple]] has relied solely on Canon Tokki in its bid to introduce its own OLED displays for the iPhones released in 2017.<ref>{{Cite news|url=https://www.bloomberg.com/news/articles/2016-12-21/apple-s-search-for-better-iphone-screens-leads-to-japan-s-rice-fields|title=Apple's Search for Better iPhone Screens Leads to Japan's Rice Fields|last1=Alpeyev|first1=Pavel|date=2016-12-21|work=Bloomberg.com|access-date=2018-05-31|last2=Amano|first2=Takashi|language=en}}</ref> The electroluminescent materials needed for OLEDs are also made by a handful of companies, some of them being Merck, Universal Display Corporation and LG Chem.<ref>{{cite web|url=https://www.oled-info.com/companies-list/oled-materials-companies|title=OLED materials companies|website=Oled-info.com}}</ref> The machines that apply these materials can operate continuously for 5–6 days, and can process a mother substrate in 5 minutes.<ref>{{cite web|url=https://www.oled-info.com/Toshiki_Tokki_Interview_Mar_2007|title=OLED-Info Q&A with Toshiki Mizoe, overseas sales manager, Tokki Corporation |website=Oled-info.com}}</ref>
OLED displays are mainly made by Samsung Display and LG Display.<ref>https://thelec.net/news/articleView.html?idxno=4247&replyAll=&reply_sc_order_by=I</ref> OLED technology is used in commercial applications such as displays for mobile phones and portable [[digital media player]]s, car radios and [[digital camera]]s among others, as well as lighting.<ref name=":0">{{Cite news|url=https://www.washingtonpost.com/news/innovations/wp/2015/01/05/what-you-need-to-know-about-oled-lighting/|title=What you need to know about OLED lighting|last=Nguyen|first=Tuan C.|date=2015-01-05|newspaper=[[The Washington Post]]|access-date=2017-09-22|language=en-US|issn=0190-8286}}</ref> Such portable display applications favor the high light output of OLEDs for readability in sunlight and their low power drain. Portable displays are also used intermittently, so the lower lifespan of organic displays is less of an issue. Prototypes have been made of flexible and rollable displays which use OLEDs' unique characteristics. Applications in flexible signs and lighting are also being developed.<ref>Michael Kanellos, [http://www.news.com/Start-up-creates-flexible-sheets-of-light/2100-11398_3-6221720.html?part=rss&tag=2547-1_3-0-5&subj=news "Start-up creates flexible sheets of light"], CNet News.com, 6 December 2007. Retrieved 20 July 2008.</ref> OLED lighting offers several advantages over LED lighting, such as higher quality illumination, more diffuse light source, and panel shapes.<ref name=":0" /> [[Philips]] Lighting has made OLED lighting samples under the brand name "Lumiblade" available online<ref>{{cite web|url=http://www.lumiblade.com |title=Philips Lumiblades |publisher=Lumiblade.com |date=2009-08-09 |access-date=2009-08-17}}</ref> and [[Novaled AG]] based in Dresden, Germany, introduced a line of OLED desk lamps called "Victory" in September, 2011.<ref>[http://www.tmcnet.com/usubmit/2011/09/13/5772879.htm Session Border Controller] {{webarchive|url=https://web.archive.org/web/20120710175419/http://www.tmcnet.com/usubmit/2011/09/13/5772879.htm |date=2012-07-10 }}. Tmcnet.com (2011-09-13). Retrieved 2012-11-12.</ref>
[[Nokia]] introduced OLED mobile phones including the [[Nokia N85|N85]] and the [[Nokia N86 8MP|N86 8MP]], both of which feature an AMOLED display. OLEDs have also been used in most [[Motorola]] and [[Samsung]] color cell phones, as well as some [[HTC Corporation|HTC]], [[LG]] and [[Sony Ericsson]] models.<ref name=cellphone>Electronic News, [http://www.edn.com/electronics-news/4323246/OLEDs-Replacing-LCDs-in-Mobile-Phones OLEDs Replacing LCDs in Mobile Phones] {{webarchive|url=https://web.archive.org/web/20161011202524/http://www.edn.com/electronics-news/4323246/OLEDs-Replacing-LCDs-in-Mobile-Phones |date=2016-10-11 }}, 7 April 2005. Retrieved 5 September 2016.</ref> OLED technology can also be found in digital media players such as the Creative [[ZEN V]], the [[iriver clix]], the [[Zune HD]] and the Sony [[Walkman X Series]].
The [[Google]] and HTC [[Nexus One]] smartphone includes an AMOLED screen, as does HTC's own [[HTC Desire|Desire]] and [[HTC Legend|Legend]] phones. However, due to supply shortages of the Samsung-produced displays, certain HTC models will use Sony's [[S-LCD|SLCD]] displays in the future,<ref>{{cite news|url=http://www.ibtimes.com/articles/38429/20100726/htc-ditches-samsung-amoled-display-for-sony-s-super-lcds.htm |title=HTC ditches Samsung AMOLED display for Sony's Super LCDs |newspaper=[[International Business Times]] |date=2010-07-26 |access-date=2010-07-30 |url-status=dead |archive-url=https://web.archive.org/web/20111001032913/http://www.ibtimes.com/articles/38429/20100726/htc-ditches-samsung-amoled-display-for-sony-s-super-lcds.htm |archive-date=1 October 2011 }}</ref> while the Google and Samsung [[Nexus S]] smartphone will use "Super Clear LCD" instead in some countries.<ref>{{cite web |url=http://www.unwiredview.com/2010/12/07/google-nexus-s-to-feature-super-clear-lcd-in-russia-and-likely-in-other-countries-too/ |title=Google Nexus S to feature Super Clear LCD in Russia (and likely in other countries, too) |publisher=UnwiredView.com |date=2010-12-07 |access-date=2010-12-08 |url-status=dead |archive-url=https://web.archive.org/web/20101210162526/http://www.unwiredview.com/2010/12/07/google-nexus-s-to-feature-super-clear-lcd-in-russia-and-likely-in-other-countries-too/ |archive-date=2010-12-10 }}</ref>
OLED displays were used in watches made by Fossil (JR-9465) and Diesel (DZ-7086). Other manufacturers of OLED panels include [[Anwell Technologies Limited]] (Hong Kong),<ref>{{cite web |url=http://www.nextinsight.com.sg/index.php/story-archive-mainmenu-60/30-2007/57-anwell-higher-profit-higher-margins-going-forward |title=ANWELL: Higher profit, higher margins going forward |publisher=nextinsight.com |date=2007-08-15 |url-status=dead |archive-url=https://web.archive.org/web/20120321145904/http://www.nextinsight.com.sg/index.php/story-archive-mainmenu-60/30-2007/57-anwell-higher-profit-higher-margins-going-forward |archive-date=21 March 2012 |access-date=27 August 2010 }}</ref> [[AU Optronics]] (Taiwan),<ref>{{cite web|url=http://auo.com/?sn=193&lang=en-US |date=2012-02-21 |title=AUO |publisher=OLED-Info.com |url-status=live |archive-url=https://web.archive.org/web/20120124105104/http://www.auo.com/?sn=193&lang=en-US |archive-date=2012-01-24 }}</ref> [[Chimei Innolux Corporation]] (Taiwan),<ref>{{cite web|url=http://www.oled-info.com/oled_panel_makers/chi_mei_el_cmel |title=Chi Mei EL (CMEL) |publisher=OLED-Info.com |url-status=live |archive-url=https://web.archive.org/web/20160105002812/http://www.oled-info.com/oled_panel_makers/chi_mei_el_cmel |archive-date=2016-01-05 }}</ref> [[LG]] (Korea),<ref>{{cite web|url=http://www.oled-info.com/lg-oled |title=LG OLEDs |publisher=OLED-Info.com |url-status=live |archive-url=https://web.archive.org/web/20160131043232/http://www.oled-info.com/lg-oled |archive-date=2016-01-31 }}</ref> and others.<ref>{{cite web|url=http://www.oled-info.com/companies |title=OLED companies |publisher=OLED-info.com |url-status=live |archive-url=https://web.archive.org/web/20160221150511/http://www.oled-info.com/companies |archive-date=2016-02-21 }}</ref>
[[DuPont]] stated in a press release in May 2010, that they can produce a 50-inch OLED TV in two minutes with a new printing technology. If this can be scaled up in terms of manufacturing, then the total cost of OLED TVs would be greatly reduced. DuPont also states that OLED TVs made with this less expensive technology can last up to 15 years if left on for a normal eight-hour day.<ref>{{cite web |url=http://www.tomsguide.com/us/OLED-Printing-Display-dupont-HDTV,news-6818.html |title=DuPont Creates 50" OLED in Under 2 Minutes |publisher=tomsguide.com |access-date=2010-06-10 |url-status=dead |archive-url=https://web.archive.org/web/20100520023829/http://www.tomsguide.com/us/OLED-Printing-Display-dupont-HDTV%2Cnews-6818.html |archive-date=2010-05-20 }}</ref><ref>{{cite web|url=http://www2.dupont.com/Displays/en_US/news_events/article20100512.html |title=DuPont Delivers OLED Technology Scalable for Television |publisher=www2.dupont.com |date=2010-05-12 |access-date=2010-05-12 |url-status=live |archive-url=https://web.archive.org/web/20100520003956/http://www2.dupont.com/Displays/en_US/news_events/article20100512.html |archive-date=2010-05-20 }}</ref>
The use of OLEDs may be subject to [[patent]]s held by [[Universal Display Corporation]], [[Eastman Kodak]], [[DuPont]], [[General Electric]], [[Philips|Royal Philips Electronics]], numerous universities and others.<ref>OLED-Info.com, [http://www.oled-info.com/tags/companies/kodak Kodak Signs OLED Cross-License Agreement] {{webarchive|url=https://web.archive.org/web/20070707115437/http://www.oled-info.com/tags/companies/kodak |date=2007-07-07 }}. Retrieved 14 March 2008.</ref> By 2008, thousands of patents associated with OLEDs, came from larger corporations and smaller technology companies.<ref name="kho2"/>
[[Flexible organic light-emitting diode|Flexible OLED]] displays have been used by manufacturers to create curved displays such as the [[Samsung Galaxy S7|Galaxy S7 Edge]] but they were not in devices that can be flexed by the users.<ref>{{cite web|url=http://www.oled-info.com/flexible-oled |title=Flexible OLED {{!}} OLED-Info |website=Oled-info.com |language=en |access-date=2017-03-25 |url-status=live |archive-url=https://web.archive.org/web/20170311053548/http://www.oled-info.com/flexible-oled |archive-date=2017-03-11 }}</ref> Samsung demonstrated a roll-out display in 2016.<ref>{{Cite news|url=http://www.techradar.com/news/samsung-galaxy-x-the-story-of-samsungs-foldable-phone-so-far |title=Samsung Galaxy X: the story of Samsung's foldable phone so far |work=TechRadar |access-date=2017-03-25 |language=en |url-status=live |archive-url=https://web.archive.org/web/20170130080932/http://www.techradar.com/news/samsung-galaxy-x-the-story-of-samsungs-foldable-phone-so-far |archive-date=2017-01-30 }}</ref>
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On 31 October 2018, [[Royole]], a Chinese electronics company, unveiled the world's first foldable screen phone featuring a flexible OLED display.<ref>{{cite web|url=https://www.theinquirer.net/inquirer/news/3065513/display-maker-royole-shows-off-worlds-first-flexible-smartphone|archive-url=https://web.archive.org/web/20181101143139/https://www.theinquirer.net/inquirer/news/3065513/display-maker-royole-shows-off-worlds-first-flexible-smartphone|url-status=unfit|archive-date=1 November 2018|title=Display maker Royole shows off 'world's first' flexible smartphone R|date=2018-11-01|website=Theinquirer.net|language=en|access-date=2019-11-27}}</ref> On 20 February 2019, [[Samsung]] announced the [[Samsung Galaxy Fold]] with a foldable OLED display from Samsung Display, its majority-owned subsidiary.<ref>{{cite web|url=https://www.theverge.com/2019/2/20/18231249/samsung-galaxy-fold-folding-phone-features-screen-photos-size-announcement|title=Samsung's foldable phone is the $1,980 Galaxy Fold|last=Warren|first=Tom|date=2019-02-20|website=Theverge.xom|access-date=2019-08-16}}</ref> At [[Mobile World Congress|MWC]] 2019 on 25 February 2019, [[Huawei]] announced the [[Huawei Mate X]] featuring a foldable OLED display from [[BOE Technology Group|BOE]].<ref>{{cite web|url=https://www.anandtech.com/show/13990/huawei-launches-the-mate-x|title=Huawei Launches the Mate X: Folding in a New Direction|last=Frumusanu|first=Andrei|website=Anandtech.com|access-date=2019-08-16}}</ref><ref>{{cite web|url=https://medium.com/@frederickyeung_59743/boe-technology-the-company-behind-huawei-mate-x-foldable-phone-8e7eb10bfaeb|title=BOE Technology: the company behind Huawei Mate X foldable phone|last=Yeung|first=Frederick|date=2019-02-27|website=Medium.com|language=en|access-date=2019-08-16}}</ref>
The 2010s also saw the wide adoption of ''tracking gate-line in pixel'' (TGP), which moves the driving circuitry from the borders of the display to in between the display's pixels, allowing for narrow bezels.<ref>{{cite web|url=http://www.cptt.com.tw/cptt/english/index.php?option=com_content&task=view&id=530&Itemid=213|archive-url=https://archive.today/20191223071353/http://www.cptt.com.tw/cptt/english/index.php?option=com_content&task=view&id=530&Itemid=213|url-status=dead|archive-date=23 December 2019|title=CHUNGHWA PICTURE TUBES, LTD. - intro_Tech|date=23 December 2019|website=Archive.ph}}</ref>
In 2023 the German startup Inuru has announced to manufacture low-cost OLED with printing for packaging and fashion applications.<ref>{{Cite web |last=Karzick |first=Lisa-Marie |date=2023-10-28 |title=Irres Konzept: So hast du OLEDs noch nie gesehen |url=https://www.inside-digital.de/news/irres-konzept-so-hast-du-oleds-noch-nie-gesehen |access-date=2023-10-28 |website=inside digital |language=de-DE}}</ref>
=== Fashion ===
Textiles incorporating OLEDs are an innovation in the fashion world and pose for a way to integrate lighting to bring inert objects to a whole new level of fashion. The hope is to combine the comfort and low cost properties of textile with the OLEDs properties of illumination and low energy consumption. Although this scenario of illuminated clothing is highly plausible, challenges are still a road block. Some issues include: the lifetime of the OLED, rigidness of flexible foil substrates, and the lack of research in making more fabric like photonic textiles.<ref>{{cite journal|last=Cherenack|first=Kunigunde|author2=Van Os, K.; Pieterson, L.|title=Smart photonic textiles begin to weave their magic|journal=Laser Focus World|date=April 2012|volume=48|issue=4|page=63}}</ref>
=== Automotive ===
The number of automakers using OLEDs is still rare and limited to the high-end of the market. For example, the 2010 [[Lexus RX]] features an OLED display instead of a thin film transistor (TFT-LCD) display.
A Japanese manufacturer [[Pioneer Electronic Corporation]] produced the first car stereos with a monochrome OLED display, which was also the world's first OLED product.<ref>{{cite web|url=http://www.novaled.com/oleds/oleds_in_display/|title=OLEDs in Display - NOVALED {{!}} Creating the OLED Revolution|website=Novaled.com|access-date=2019-11-27}}</ref> The Aston Martin DB9 incorporated the world's first automotive OLED display,<ref>{{cite web|url=https://www.pcworld.com/article/119722/article.html|title=OLED: New Star of the Small Screen|date=2005-03-01|website=PCWorld.com|language=en|access-date=2019-11-27|archive-date=6 August 2020|archive-url=https://web.archive.org/web/20200806024946/https://www.pcworld.com/article/119722/article.html|url-status=dead}}</ref> which was manufactured by [[Yazaki]],<ref>{{Cite web|url=https://www.yazaki-europe.com/fileadmin/user_upload/News/2016/Press_Media/Company_History_English.pdf|title=Company History English|website=Yazaki-europe.com|access-date=5 March 2022}}</ref> followed by the 2004 Jeep Grand Cherokee and the Chevrolet Corvette C6.<ref>{{cite web|url=https://www.extremetech.com/extreme/74378-oleds-now-lighting-up-automobiles-report-says|title=OLEDs Now Lighting Up Automobiles, Report Says - ExtremeTech|website=Extremetech.com|access-date=2019-11-27}}</ref> The 2015 [[Hyundai Sonata]] and [[Kia Soul]] EV use a 3.5-inch white PMOLED display.
===Company-specific applications===
====Samsung====
[[File:Dynamic AMOLED.jpg|thumb|Samsung AMOLED displays]]
By 2004, Samsung Display, a subsidiary of [[South Korea]]'s largest [[conglomerate (company)|conglomerate]] and a former Samsung-[[NEC]] joint venture, was the world's largest OLED manufacturer, producing 40% of the OLED displays made in the world,<ref>{{cite web|url=http://www.oled-info.com/market_reports/samsung_sdi_the_worlds_largest_oled_display_maker |title=Samsung SDI{{nbsp}}– The world's largest OLED display maker |publisher=Oled-info.com |access-date=2009-08-17 |url-status=live |archive-url=https://web.archive.org/web/20090622171805/http://www.oled-info.com/market_reports/samsung_sdi_the_worlds_largest_oled_display_maker |archive-date=2009-06-22 }}</ref> and as of 2010, has a 98% share of the global [[AMOLED]] market.<ref>{{cite news|url=https://www.koreatimes.co.kr/www/news/biz/2010/07/123_69626.html |title=Samsung, LG in legal fight over brain drain |newspaper=[[The Korea Times]] |date=2010-07-17 |access-date=2010-07-30 |url-status=live |archive-url=https://web.archive.org/web/20100721124657/http://www.koreatimes.co.kr/www/news/biz/2010/07/123_69626.html |archive-date=2010-07-21 }}</ref> The company is leading the world of OLED industry, generating $100.2{{nbsp}}million out of the total $475{{nbsp}}million revenues in the global OLED market in 2006.<ref name="findarticles.com">{{cite news|url=http://findarticles.com/p/articles/mi_m0EIN/is_2008_July_17/ai_n27929051 |title=Frost & Sullivan Recognizes Samsung SDI for Market Leadership in the OLED Display Market &#124; Find Articles at BNET |publisher=Findarticles.com |date=2008-07-17 |access-date=2009-08-17 |url-status=dead |archive-url=https://web.archive.org/web/20090522000822/http://findarticles.com/p/articles/mi_m0EIN/is_2008_July_17/ai_n27929051/ |archive-date=2009-05-22 }}</ref> As of 2006, it held more than 600 American patents and more than 2800 international patents, making it the largest owner of AMOLED technology patents.<ref name="findarticles.com"/>
Samsung SDI announced in 2005, the world's largest OLED TV at the time, at {{convert|21|in|cm}}.<ref>{{cite web|url=http://www.physorg.com/news2547.html |title=World's Largest 21-inch OLED for TVs from Samsung |publisher=Physorg.com |date=2005-01-04 |access-date=2009-08-17 |url-status=live |archive-url=https://web.archive.org/web/20090112075717/http://www.physorg.com/news2547.html |archive-date=2009-01-12 }}</ref> This OLED featured the highest resolution at the time, of 6.22{{nbsp}}million pixels. In addition, the company adopted active matrix-based technology for its low power consumption and high-resolution qualities. This was exceeded in January 2008, when Samsung showcased the world's largest and thinnest OLED TV at the time, at 31{{nbsp}}inches (78{{nbsp}}cm) and 4.3{{nbsp}}mm.<ref>{{cite web|last=Robischon |first=Noah |url=https://gizmodo.com/342912/samsungs-31+inch-oled-is-biggest-thinnest-yet |title=Samsung's 31-Inch OLED Is Biggest, Thinnest Yet&nbsp;– AM-OLED |website=Gizmodo.com |date=2008-01-09 |access-date=2009-08-17 |url-status=live |archive-url=https://web.archive.org/web/20090810035723/http://gizmodo.com/342912/samsungs-31%20inch-oled-is-biggest-thinnest-yet |archive-date=2009-08-10 }}</ref>
In May 2008, Samsung unveiled an ultra-thin 12.1{{nbsp}}inch (30{{nbsp}}cm) laptop OLED display concept, with a 1,280×768 resolution with infinite contrast ratio.<ref>{{cite web|last=Ricker |first=Thomas |url=https://www.engadget.com/2008/05/16/samsungs-12-1-inch-oled-laptop-makes-us-swoon/ |title=Samsung's 12.1-inch OLED laptop concept makes us swoon |website=Engadget.com |date=2008-05-16 |access-date=2009-08-17 |url-status=live |archive-url=https://web.archive.org/web/20091007032757/http://www.engadget.com/2008/05/16/samsungs-12-1-inch-oled-laptop-makes-us-swoon/ |archive-date=2009-10-07 }}</ref> According to Woo Jong Lee, Vice President of the Mobile Display Marketing Team at Samsung SDI, the company expected OLED displays to be used in notebook PCs as soon as 2010.<ref>{{cite web|url=http://www.trustedreviews.com/notebooks/news/2008/12/03/Samsung--OLED-Notebooks-In-2010/p1 |title=Samsung: OLED Notebooks In 2010 |website=TrustedReviews.com |access-date=2009-08-17 |url-status=live |archive-url=https://web.archive.org/web/20090416182826/http://www.trustedreviews.com/notebooks/news/2008/12/03/Samsung--OLED-Notebooks-In-2010/p1 |archive-date=2009-04-16 }}</ref>
In October 2008, Samsung showcased the world's thinnest OLED display, also the first to be "flappable" and bendable.<ref name="flapping">{{cite web|author1=Takuya Otani |author2=Nikkei Electronics |url=http://techon.nikkeibp.co.jp/english/NEWS_EN/20081029/160349/ |title=[FPDI&#93; Samsung Unveils 0.05mm 'Flapping' OLED Panel&nbsp;– Tech-On! |publisher=Techon.nikkeibp.co.jp |date=2008-10-29 |access-date=2009-08-17 |url-status=live |archive-url=https://web.archive.org/web/20081127175913/http://techon.nikkeibp.co.jp/english/NEWS_EN/20081029/160349/ |archive-date=2008-11-27 }}</ref> It measures just 0.05{{nbsp}}mm (thinner than paper), yet a Samsung staff member said that it is "technically possible to make the panel thinner".<ref name="flapping" /> To achieve this thickness, Samsung etched an OLED panel that uses a normal glass substrate. The drive circuit was formed by low-temperature polysilicon TFTs. Also, low-molecular organic EL materials were employed. The pixel count of the display is 480 × 272. The contrast ratio is 100,000:1, and the luminance is 200{{nbsp}}cd/m<sup>2</sup>. The colour reproduction range is 100% of the NTSC standard.
At the [[Consumer Electronics Show|Consumer Electronics Show (CES)]] in January 2010, Samsung demonstrated a laptop computer with a large, transparent OLED display featuring up to 40% transparency<ref name="laptoptransparent">{{cite web|url=http://www.thedesignblog.org/entry/samsung-presents-worlds-first-and-largest-transparent-oled-laptop-at-ces/ |title=Samsung presents world's first and largest transparent OLED laptop at CES |date=2010-01-07 |url-status=dead |archive-url=https://web.archive.org/web/20100111090105/http://www.thedesignblog.org/entry/samsung-presents-worlds-first-and-largest-transparent-oled-laptop-at-ces |archive-date=11 January 2010 }}</ref> and an animated OLED display in a photo ID card.<ref name="photoid">{{cite web |url=http://ces.cnet.com/8301-31045_1-10429565-269.html |title=CES: Samsung shows OLED display in a photo card |date=2010-01-07 |url-status=dead |archive-url=https://web.archive.org/web/20111220215714/http://ces.cnet.com/8301-31045_1-10429565-269.html |archive-date=20 December 2011 |access-date=10 January 2010 }}</ref>
Samsung's 2010 AMOLED smartphones used their [[Super AMOLED]] trademark, with the [[Samsung Wave S8500]] and [[Samsung i9000 Galaxy S]] being launched in June 2010. In January 2011, Samsung announced their Super AMOLED Plus displays, which offer several advances over the older [[Super AMOLED]] displays: real stripe matrix (50% more sub pixels), thinner form factor, brighter image and an 18% reduction in energy consumption.<ref name="Super-Amoled-PLus">{{cite web|url=http://www.oled-info.com/samsung-announces-super-amoled-plus-displays |title=Samsung Super AMOLED Plus display announced |access-date=2011-01-06 |url-status=live |archive-url=https://web.archive.org/web/20110109144825/http://www.oled-info.com/samsung-announces-super-amoled-plus-displays |archive-date=2011-01-09 }}</ref>
At CES 2012, Samsung introduced the first 55" TV screen that uses Super OLED technology.<ref name="CES-2012-review">{{cite web|last=Clark |first=Shaylin |date=2012-01-12 |url=http://www.webpronews.com/ces-2012-samsung-oled-awards-2012-01 |title=CES 2012 Samsung's OLED TV Rakes In Awards |publisher=WebProNews |access-date=2012-12-03 |url-status=live |archive-url=https://web.archive.org/web/20121124171414/http://www.webpronews.com/ces-2012-samsung-oled-awards-2012-01 |archive-date=2012-11-24 }}</ref>
On 8 January 2013, at CES Samsung unveiled a unique curved 4K Ultra S9 OLED television, which they state provides an "IMAX-like experience" for viewers.<ref name="Samsung's curved OLED TV provides an 'IMAX-like' experience">Rougeau, Michael (2013-01-08). [http://www.techradar.com/news/television/hdtv/samsungs-curved-oled-tv-provides-an-imax-like-experience-1123683 Samsung's curved OLED TV provides an 'IMAX-like' experience] {{webarchive|url=https://web.archive.org/web/20130111023711/http://www.techradar.com/news/television/hdtv/samsungs-curved-oled-tv-provides-an-imax-like-experience-1123683 |date=2013-01-11 }}. Techradar. Retrieved 2013-01-08.</ref>
On 13 August 2013, Samsung announced availability of a 55-inch curved OLED TV (model KN55S9C) in the US at a price point of $8999.99.<ref>Boylan, Chris (2013-08-13). [http://www.bigpicturebigsound.com/Bring-Out-Your-OLED-Samsung-KN55S9C-OLED-TV-Available-Now-for-8999-99.shtml "Bring Out Your OLED: Samsung KN55S9C OLED TV Available Now for $8999.99"] {{webarchive|url=https://web.archive.org/web/20130817095131/http://www.bigpicturebigsound.com/Bring-Out-Your-OLED-Samsung-KN55S9C-OLED-TV-Available-Now-for-8999-99.shtml |date=2013-08-17 }}. Big Picture Big Sound. Retrieved 2013-08-13.</ref>
On 6 September 2013, Samsung launched its 55-inch curved OLED TV (model KE55S9C) in the United Kingdom with John Lewis.<ref>{{cite web|title=John Lewis TV Gallery video: 4K and OLED from Samsung, Sony, LG and Panasonic |url=http://recombu.com/digital/news/john-lewis-tv-gallery-video-4k-and-oled-from-samsung-sony-lg-and-panasonic_M12106.html |publisher=Recombu |access-date=26 September 2013 |author=Alex Lane |date=6 September 2013 |url-status=live |archive-url=https://web.archive.org/web/20130927170425/http://recombu.com/digital/news/john-lewis-tv-gallery-video-4k-and-oled-from-samsung-sony-lg-and-panasonic_M12106.html |archive-date=27 September 2013 }}</ref>
Samsung introduced the ''Galaxy Round'' smartphone in the Korean market in October 2013. The device features a 1080p screen, measuring {{convert|5.7|in|cm}}, that curves on the vertical axis in a rounded case. The corporation has promoted the following advantages: A new feature called "Round Interaction" that allows users to look at information by tilting the handset on a flat surface with the screen off, and the feel of one continuous transition when the user switches between home screens.<ref>{{cite web|title=Samsung's Galaxy Round is the first phone with a curved display |url=https://www.theverge.com/2013/10/8/4818572/samsung-galaxy-round-curved-oled-smartphone-official |website=Theverge.com |publisher=[[Vox Media, Inc]] |access-date=10 November 2013 |author=Sam Byford |date=8 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20131109081356/http://www.theverge.com/2013/10/8/4818572/samsung-galaxy-round-curved-oled-smartphone-official |archive-date=9 November 2013 }}</ref>
Samsung released a new line of OLED TVs in 2022, its first using the technology since 2013.<ref>{{Cite web |date=2022-03-31 |title=Samsung's new 2022 TVs are here, including its first OLED in nearly a decade |url=https://www.cnn.com/cnn-underscored/electronics/samsung-new-tv-soundbar-lineup-2022 |access-date=2022-04-20 |website=CNN Underscored |language=en}}</ref> They use panels sourced from Samsung Display; previously, LG was the sole manufacturer of OLED panels for TVs.<ref>{{Cite web |last=Welch |first=Chris |date=2022-04-04 |title=I saw Samsung's first-ever QD-OLED TV, and it's impressive |url=https://www.theverge.com/2022/4/4/23009841/samsung-qd-oled-tv-s95b-preview |access-date=2022-04-20 |website=The Verge |language=en}}</ref>
====Sony====
[[File:Sony oled.jpg|thumb|[[Sony XEL-1]], the world's first OLED TV<ref name="xel1"/> (front)]]
The [[Sony CLIÉ PEG-VZ90]] was released in 2004, being the first PDA to feature an OLED screen.<ref>{{cite web|url=https://www.engadget.com/2004/09/14/sonys-clie-peg-vz90-the-worlds-most-expensive-palm/ |title=Sony's Clie PEG-VZ90—the world's most expensive Palm? |website=Engadget.com |date=2004-09-14 |access-date=2010-07-30 |url-status=live |archive-url=https://web.archive.org/web/20100209011807/http://www.engadget.com/2004/09/14/sonys-clie-peg-vz90-the-worlds-most-expensive-palm |archive-date=2010-02-09 }}</ref> Other Sony products to feature OLED screens include the MZ-RH1 portable minidisc recorder, released in 2006<ref>{{cite web|url=http://www.minidisc.org/part_Sony_MZ-RH1.html |title=MD Community Page: Sony MZ-RH1 |publisher=Minidisc.org |date=2007-02-24 |access-date=2009-08-17 |url-status=live |archive-url=https://web.archive.org/web/20090520053956/http://www.minidisc.org/part_Sony_MZ-RH1.html |archive-date=2009-05-20 }}</ref> and the [[Walkman X Series]].<ref>{{cite web|url=http://www.slashgear.com/sony-nwz-x1000-series-oled-walkman-specs-released-0936896/ |title=Sony NWZ-X1000-series OLED Walkman specs released |publisher=Slashgear |date=2009-03-09 |access-date=2011-01-01 |url-status=live |archive-url=https://web.archive.org/web/20110204105047/http://www.slashgear.com/sony-nwz-x1000-series-oled-walkman-specs-released-0936896/ |archive-date=2011-02-04 }}</ref>
At the 2007, [[Las Vegas Valley|Las Vegas]] [[Consumer Electronics Show]] (CES), Sony showcased a {{convert|11|in|cm|adj=on}}, (resolution 960×540) and {{convert|27|in|cm|adj=on}}, full HD resolution at {{nowrap|1920 × 1080}} OLED TV models.<ref>"Sony announces a {{cvt|27|in|cm|adj=on}} OLED TV". HDTV Info Europe (2008-05-29)</ref> Both claimed 1,000,000:1 [[contrast ratio]]s and total thicknesses (including bezels) of 5{{nbsp}}mm. In April 2007, Sony announced it would manufacture 1000 {{convert|11|in|cm|adj=on}} OLED TVs per month for market testing purposes.<ref>CNET News, [http://news.cnet.co.uk/televisions/0,39029698,49289103,00.htm Sony to sell 11-inch OLED TV this year], 12 April 2007. Retrieved 28 July 2007.  {{webarchive|url=https://web.archive.org/web/20070604201639/http://news.cnet.co.uk/televisions/0%2C39029698%2C49289103%2C00.htm |date=4 June 2007 }}</ref> On 1 October 2007, Sony announced that the {{convert|11|in|cm|adj=on}} model [[Sony XEL-1|XEL-1]], was the first commercial OLED TV<ref name="xel1">[http://www.oled-info.com/sony-xel-1 Sony XEL-1:The world's first OLED TV] {{webarchive|url=https://web.archive.org/web/20160205034833/http://www.oled-info.com/sony-xel-1 |date=2016-02-05 }}, OLED-Info.com (2008-11-17).</ref> and it was released in Japan in December 2007.<ref>[https://www.engadget.com/2007/10/01/the-sonydrive-xel-1-oled-tv-1-000-000-1-contrast-starting-decem/ The Sony Drive XEL-1 OLED TV: 1,000,000:1 contrast starting 1 December] {{webarchive|url=https://web.archive.org/web/20071004073101/http://www.engadget.com/2007/10/01/the-sonydrive-xel-1-oled-tv-1-000-000-1-contrast-starting-decem/ |date=2007-10-04 }}, Engadget (2007-10-01).</ref>
In May 2007, Sony publicly unveiled a video of a {{convert|2.5|in|cm|adj=on}} flexible OLED screen which is only 0.3 millimeters thick.<ref>{{cite web|url=http://www.gizmowatch.com/entry/sony-claims-development-of-worlds-first-flexible-full-color-oled-display/ |archive-url=https://web.archive.org/web/20071017194310/http://www.gizmowatch.com/entry/sony-claims-development-of-worlds-first-flexible-full-color-oled-display/ |url-status=dead |archive-date=2007-10-17 |title=Sony claims development of world's first flexible, full-color OLED display |publisher=Gizmo Watch |date=2007-05-25 |access-date=2010-07-30 }}</ref> At the Display 2008 exhibition, Sony demonstrated a 0.2{{nbsp}}mm thick {{convert|3.5|in|cm}} display with a resolution of 320×200 pixels and a 0.3{{nbsp}}mm thick {{convert|11|in|cm|adj=on}} display with 960×540 pixels resolution, one-tenth the thickness of the XEL-1.<ref>[https://www.engadget.com/2008/04/16/sonys-3-5-inch-oled-is-just-0-0079-inches-thin/ Sony's 3.5- and 11-inch OLEDs are just 0.008- and 0.012-inches thin] {{webarchive|url=https://web.archive.org/web/20160105002812/http://www.engadget.com/2008/04/16/sonys-3-5-inch-oled-is-just-0-0079-inches-thin/ |date=2016-01-05 }}. Engadget (2008-04-16). Retrieved 2011-10-04.</ref><ref>[http://www.watch.impress.co.jp/av/docs/20080416/display1.htm (Display 2008)開幕.ソニーの0.3mm有機ELパネルなど-150型プラズマやビクターの3D技術など] {{webarchive|url=https://web.archive.org/web/20080629215946/http://www.watch.impress.co.jp/av/docs/20080416/display1.htm |date=2008-06-29 }}. impress.co.jp (2008-04-16)</ref>
In July 2008, a Japanese government body said it would fund a joint project of leading firms, which is to develop a key technology to produce large, energy-saving organic displays. The project involves one laboratory and 10 companies including Sony Corp. [[New Energy and Industrial Technology Development Organization|NEDO]] said the project was aimed at developing a core technology to mass-produce 40{{nbsp}}inch or larger OLED displays in the late 2010s.<ref>[http://afp.google.com/article/ALeqM5g2t17vPrJMIIq_w8_30RypVmyP_g Japanese firms team up on energy-saving OLED panels], AFP (2008-07-10). {{webarchive |url=https://web.archive.org/web/20130605194612/http://afp.google.com/article/ALeqM5g2t17vPrJMIIq_w8_30RypVmyP_g |date=5 June 2013 }}</ref>
In October 2008, Sony published results of research it carried out with the [[Max Planck Institute]] over the possibility of mass-market bending displays, which could replace rigid LCDs and plasma screens. Eventually, bendable, [[see-through display]]s could be stacked to produce 3D images with much greater contrast ratios and [[viewing angle]]s than existing products.<ref>{{cite web|last=Athowon |first=Desire |url=http://www.itproportal.com/articles/2008/10/04/sony-working-bendable-folding-oled-screens/ |title=Sony Working on Bendable, Folding OLED Screens |publisher=ITProPortal.com |year=2008 |url-status=dead |archive-url=https://web.archive.org/web/20081009004333/http://www.itproportal.com/articles/2008/10/04/sony-working-bendable-folding-oled-screens/ |archive-date=9 October 2008 }}</ref>
Sony exhibited a 24.5" (62{{nbsp}}cm) prototype OLED 3D television during the Consumer Electronics Show in January 2010.<ref name="engadget1">{{cite web|url=https://www.engadget.com/2010/01/07/sony-oled-3d-tv-eyes-on/ |title=Sony OLED 3D TV eyes-on |website=Engadget.com |date=7 January 2010 |access-date=2010-01-11 |url-status=live |archive-url=https://web.archive.org/web/20100110231818/http://www.engadget.com/2010/01/07/sony-oled-3d-tv-eyes-on/ |archive-date=2010-01-10 }}</ref>
In January 2011, Sony announced the [[PlayStation Vita]] handheld game console (the successor to the [[PlayStation Portable|PSP]]) will feature a 5-inch OLED screen.<ref name="usatoday">{{cite news|url=https://www.usatoday.com/tech/products/2011-01-28-sonyportable28_ST_N.htm |title=Sony unveils NGP, its new portable gaming device |work=USA Today |date= 2011-01-28|access-date=2011-01-27 |first=Mike |last=Snider}}</ref>
On 17 February 2011, Sony announced its 25" (63.5{{nbsp}}cm) OLED Professional Reference Monitor aimed at the Cinema and high end Drama Post Production market.<ref name="Sony Professional">{{cite web|url=http://www.sony.co.uk/biz/content/id/1237480397754/section/broadcast-news/ |title=Sony Professional Reference Monitor |publisher=Sony |access-date=2011-02-17 |url-status=live |archive-url=https://web.archive.org/web/20120308152943/http://www.sony.co.uk/biz/content/id/1237480397754/section/broadcast-news/ |archive-date=2012-03-08 }}</ref>
On 25 June 2012, Sony and Panasonic announced a joint venture for creating low cost mass production OLED televisions by 2013.<ref name="sonypan">{{cite web | url=http://www.mail.com/scitech/news/1385290-sony-panasonic-tying-up-advanced-tv-displays.html#.7518-stage-set2-4 | title=Sony, Panasonic tying up in advanced TV displays | date=25 June 2012}}</ref>
Sony unveiled its first OLED TV since 2008 at [[CES 2017]] called A1E. It revealed two other models in 2018 one at [[CES 2018]] called A8F and other a Master Series TV called A9F. At [[CES 2019]] they unveiled another two models one the A8G and the other another Bravia Series TV called A9G. Then, at [[CES 2020]], they revealed the A8H, which was effectively an A9G in terms of picture quality but with some compromises due to its lower cost. At the same event, they also revealed a 48-inch version of the A9G, making this its smallest OLED TV since the XEL-1.<ref>{{cite web|url=https://www.sony.com/electronics/tv/t/televisions|title=Televisions &#124; Smart TVs, 4K and Flat Screen LED TVs &#124; Sony US|website=Sony.com}}</ref><ref>{{cite web|url=https://www.engadget.com/2017/01/06/sony-at-ces-2017-everything-you-need-to-know/|title=Sony at CES 2017: Everything you need to know|website=Engadget.com|date=19 July 2019 }}</ref><ref>{{cite web|url=https://www.engadget.com/2018/01/08/watch-sony-ces-2018-event/|title=Watch Sony's CES 2018 event right here at 8PM ET|website=Engadget.com|date=19 July 2019 }}</ref><ref>{{cite web|url=https://www.engadget.com/2019/01/07/sony-ces-2019-liveblog/|title=Live from Sony's CES 2019 press event!|website=Engadget.com|date=9 August 2019 }}</ref>
====LG====
On 9 April 2009, LG acquired [[Kodak]]'s OLED business and started to utilize white OLED technology.<ref>{{cite web|url=https://gizmodo.com/kodaks-slow-fade-inventor-of-oled-sells-oled-business-5418985|title=Kodak's Slow Fade: Inventor of OLED Sells OLED Business|last=Barrett|first=Brian|website=Gizmodo.com|date=4 December 2009 |language=en-US|access-date=2019-10-05}}</ref><ref>{{cite web|url=https://www.cnet.com/news/lg-says-white-oled-gives-it-ten-years-on-tv-competition/|title=LG says white OLED puts it a decade ahead of competitors|last=Byrne|first=Seamus|website=Cnet.com|language=en|access-date=2019-10-06}}</ref> As of 2010, [[LG Electronics]] produced one model of OLED television, the {{convert|15|in|cm|adj=on}} 15EL9500<ref name="LG">[http://www.lg.com/uk/tv-audio-video/televisions/LG-oled-tv-15EL9500.jsp LG 15EL9500 OLED Television] {{webarchive|url=https://web.archive.org/web/20120414081133/http://www.lg.com/uk/tv-audio-video/televisions/LG-oled-tv-15EL9500.jsp |date=2012-04-14 }}. Lg.com. Retrieved 2011-10-04.</ref> and had announced a {{convert|31|in|cm|adj=on}} OLED 3D television for March 2011.<ref>[http://www.electricpig.co.uk/2010/09/03/lg-31-inch-oled-tv-on-sale-march-for-6000/ LG announces 31" OLED 3DTV] {{webarchive|url=https://web.archive.org/web/20160304002205/http://www.electricpig.co.uk/2010/09/03/lg-31-inch-oled-tv-on-sale-march-for-6000/ |date=2016-03-04 }}. Electricpig.co.uk (2010-09-03). Retrieved 2011-10-04.</ref> On 26 December 2011, LG officially announced the "world's largest {{convert|55|in|cm|adj=on}} OLED panel" and featured it at CES 2012.<ref>[https://www.engadget.com/2011/12/25/lgs-55-inch-worlds-largest-oled-hdtv-panel-is-official-comi/ LG's 55-inch 'world's largest' OLED HDTV panel is official, coming to CES 2012] {{webarchive|url=https://web.archive.org/web/20111226061810/http://www.engadget.com/2011/12/25/lgs-55-inch-worlds-largest-oled-hdtv-panel-is-official-comi/ |date=2011-12-26 }}. Engadget (2011-12-25). Retrieved 2012-11-12.</ref> In late 2012, LG announces the launch of the 55EM9600 OLED television in Australia.<ref>[http://www.lg.com/au/oled-tv OLED TV]. LG (2010-09-03). Retrieved 2012-12-21.</ref>
In January 2015, LG Display signed a long-term agreement with Universal Display Corporation for the supply of OLED materials and the right to use their patented OLED emitters.<ref>{{cite web|url=https://finance.yahoo.com/|archive-url=https://web.archive.org/web/20150131011914/http://biz.yahoo.com/e/150126/oled8-k.html|url-status=dead|title=Yahoo Finance - Business Finance, Stock Market, Quotes, News|archive-date=31 January 2015|website=Finance.yahoo.com}}</ref>
As of 2022, LG produces the world's largest OLED TV, at 97 inches.<ref>{{Cite web |url=https://www.techradar.com/news/lg-to-showcase-worlds-largest-oled-tv-its-a-97-inch-stunner |title=LG to showcase world's largest OLED TV - It's a 97-inch stunner |date=2022-08-29 |access-date=2024-08-26 |website=[[TechRadar]] |last=K |first=Balakumar}}</ref><ref>{{Cite web |url=https://www.tomsguide.com/news/lg-is-making-the-worlds-largest-oled-tv-and-its-going-on-sale-soon |title=LG is making the world's largest OLED TV — and it's going on sale soon |date=2022-09-05 |access-date=2024-08-26 |website=[[Tom's Guide]] |last=Pino |first=Nick}}</ref>
====Mitsubishi====
Lumiotec is the first company in the world developing and selling, since January 2011, mass-produced OLED lighting panels with such brightness and long lifetime. Lumiotec is a joint venture of Mitsubishi Heavy Industries, ROHM, Toppan Printing, and Mitsui & Co.
On 1 June 2011, [[Mitsubishi Electric]] installed a 6-meter OLED 'sphere' in Tokyo's Science Museum.<ref>[http://www.mitsubishielectric.com/news/2011/0601.html MITSUBISHI ELECTRIC News Releases Installs 6-Meter OLED Globe at Science Museum] {{webarchive|url=https://web.archive.org/web/20120723071206/http://mitsubishielectric.com/news/2011/0601.html |date=2012-07-23 }}. Mitsubishielectric.com (2011-06-01). Retrieved 2012-11-12.</ref>
====Recom Group====
On 6 January 2011, Los Angeles-based technology company Recom Group introduced the first small screen consumer application of the OLED at the Consumer Electronics Show in Las Vegas. This was a 2.8" (7{{nbsp}}cm) OLED display being used as a wearable video name tag.<ref>Coxworth, Ben (2011-03-31). [http://www.gizmag.com/video-name-tag-wearable-oled-screen/18291/ Video Name Tags turn salespeople into walking TV commercials] {{webarchive|url=https://web.archive.org/web/20111222043505/http://www.gizmag.com/video-name-tag-wearable-oled-screen/18291/ |date=2011-12-22 }}. Gizmag.com. Retrieved 2012-11-12.</ref> At the Consumer Electronics Show in 2012, Recom Group introduced the world's first video mic flag incorporating three 2.8" (7{{nbsp}}cm) OLED displays on a standard broadcaster's mic flag. The video mic flag allowed video content and advertising to be shown on a broadcasters standard mic flag.<ref>[http://firstpost.com/topic/organization/cbs-three-minutes-of-video-every-broadcaster-and-advertiser-must-video-wygkuztf7L8-31428-1.html Three Minutes of Video Every Broadcaster and Advertiser MUST SEE.avi – CBS Videos : Firstpost Topic – Page 1] {{webarchive|url=https://web.archive.org/web/20120723195818/http://firstpost.com/topic/organization/cbs-three-minutes-of-video-every-broadcaster-and-advertiser-must-video-wygkuztf7L8-31428-1.html|date=2012-07-23}}. Firstpost.com (2012-08-10). Retrieved 2012-11-12.</ref>
====Dell====
On 6 January 2016, Dell announced the Ultrasharp UP3017Q OLED monitor at the Consumer Electronics Show in Las Vegas.<ref>{{Cite news|url=http://www.pcworld.com/article/3018710/hardware/dell-unveils-stunning-4k-oled-ultrasharp-display-and-declares-war-on-bezels.html|title=Dell unveils stunning 4K OLED UltraSharp display and declares war on bezels|work=PCWorld|access-date=2017-06-20|language=en}}</ref> The monitor was announced to feature a {{convert|30|in|cm|adj=on}} 4K UHD OLED panel with a 120{{nbsp}}Hz refresh rate, 0.1 millisecond response time, and a contrast ratio of 400,000:1. The monitor was set to sell at a price of $4,999 and release in March, 2016, just a few months later. As the end of March rolled around, the monitor was not released to the market and Dell did not speak on reasons for the delay. Reports suggested that Dell canceled the monitor as the company was unhappy with the image quality of the OLED panel, especially the amount of color drift that it displayed when you viewed the monitor from the sides.<ref>{{cite web|url=https://www.oled-info.com/oled-monitor|title=OLED monitor: market status and updates |website=Oled-info.com|language=en|access-date=2017-06-20}}</ref> On 13 April 2017, Dell finally released the UP3017Q OLED monitor to the market at a price of $3,499 ($1,500 less than its original spoken price of $4,999 at CES 2016). In addition to the price drop, the monitor featured a 60{{nbsp}}Hz refresh rate and a contrast ratio of 1,000,000:1. As of June, 2017, the monitor is no longer available to purchase from Dell's website.
====Apple====
[[Apple Inc.|Apple]] began using OLED panels in its watches in 2015 and in its laptops in 2016 with the introduction of an OLED touchbar to the MacBook Pro.<ref>{{Cite news|url=https://www.engadget.com/2016/10/27/apple-unveils-a-thinner-macbook-pro-with-oled-touch-strip/|title=Apple unveils a thinner MacBook Pro with an OLED 'Touch Bar'|work=Engadget|access-date=2017-09-22|language=en-US}}</ref> In 2017, Apple announced the introduction of their tenth anniversary [[iPhone X]] with their own optimized OLED display licensed from Universal Display Corporation.<ref>{{Cite news|url=https://www.macworld.com/article/3223143/displays/oled-vs-lcd-how-the-iphone-xs-display-changes-everything.html|title=OLED vs LCD: How the iPhone X's display changes everything|work=Macworld|access-date=2017-09-22|language=en}}</ref> With the exception of the [[iPhone SE]] line, iPhone XR and iPhone 11, all iPhones released since then have also featured OLED displays. In 2024, Apple announced the [[IPad Pro (7th generation)|7th generation iPad Pro]], which featured a "tandem OLED"<ref>{{Cite web |author1=Matt Bolton |date=2024-05-08 |title=The iPad Pro 2024's new Tandem OLED screen explained: why it's important, and why it took so long to come |url=https://www.techradar.com/tablets/ipad-pro/the-ipad-pro-2024s-new-tandem-oled-screen-explained-why-its-important-and-why-it-took-so-long-to-come |access-date=2024-06-07 |website=TechRadar |language=en}}</ref> panel in an attempt to increase the panel's brightness.
====Nintendo====
A third model of [[Nintendo]]'s [[Nintendo Switch|Switch]], a hybrid gaming system, features an OLED panel in place of the original model's [[Liquid-crystal display|LCD]] panel. Announced in the summer of 2021, it was released on 8 October 2021.<ref>{{cite web|title=Nintendo Switch OLED model - Nintendo - Official Site|url=https://www.nintendo.com/switch/oled-model/|access-date=2021-07-06|website=Nintendo.com|language=en-US}}</ref>
== Research ==
In 2014, [[Mitsubishi Chemical Corporation]] (MCC), a subsidiary of [[Mitsubishi Chemical Holdings]], developed an OLED panel with a 30,000-hour life, twice that of conventional OLED panels.<ref>[http://www.globalpost.com/dispatch/news/xinhua-news-agency/141013/japanese-company-doubles-diode-panels-life-span Japanese company doubles diode panel's life span] {{webarchive|url=https://web.archive.org/web/20141029234321/http://www.globalpost.com/dispatch/news/xinhua-news-agency/141013/japanese-company-doubles-diode-panels-life-span |date=2014-10-29 }}, Global Post, 13 October 2014</ref>
The search for efficient OLED materials has been extensively supported by simulation methods; it is possible to calculate important properties computationally, independent of experimental input,<ref>[http://www.mpip-mainz.mpg.de/molecules_to_OLED From Molecules to Organic Light Emitting Diodes] {{webarchive|url=https://web.archive.org/web/20150415181006/http://www.mpip-mainz.mpg.de/molecules_to_OLED |date=2015-04-15 }}, Max Planck Institute for Polymer Research, 7 April 2015.</ref><ref>{{cite journal|doi=10.1002/adfm.201403004|title=Modeling of Organic Light Emitting Diodes: From Molecular to Device Properties|year=2015|last1=Kordt|first1=Pascal|journal=Advanced Functional Materials|volume=25|pages=1955–1971|issue=13|display-authors=etal|hdl=21.11116/0000-0001-6CD1-A|s2cid=18575622|hdl-access=free}}</ref> making materials development cheaper.
On 18 October 2018, [[Samsung]] showed of their research roadmap at their 2018 Samsung OLED Forum. This included Fingerprint on Display (FoD), Under Panel Sensor (UPS), Haptic on Display (HoD) and Sound on Display (SoD).<ref>{{cite web|url=https://www.gsmarena.com/samsung_is_working_on_an_indisplay_frontfacing_camera-news-33821.php|title=Samsung is working on an in-display front-facing camera|website=GSMArena.com|language=en-US|access-date=2019-08-16}}</ref>
Various venders are also researching cameras under OLEDs (Under Display Cameras). According to IHS Markit [[Huawei]] has partnered with [[BOE Technology Group|BOE]], [[Oppo]] with China Star Optoelectronics Technology (CSOT), [[Xiaomi]] with [[Visionox]].<ref>{{cite web|url=http://www.instantflashnews.com/en/2019/08/05/08-05-apples-2021-iphones-will-allegedly-come-with-face-id-and-on-screen-fingerprint-sensors-huawei-is-allegedly-busy-testing-its-smartphone-armed-with-self-developed-hongmeng-os-etc/|title=08-05: Apple's 2021 iPhones will allegedly come with Face ID and on-screen fingerprint sensors; Huawei is allegedly busy testing its smartphone armed with self-developed HongMeng OS; etc.|date=2019-08-05|website=Instantflashnews.com|language=en-US|access-date=2019-08-16}}</ref>
In 2020, researchers at the [[Queensland University of Technology]] (QUT) proposed using [[human hair]] which is a source of carbon and nitrogen to create OLED displays.<ref>{{cite news |url=https://newatlas.com/electronics/human-hair-carbon-dot-oled/ |title=Discarded human hair repurposed to make new OLED screens |newspaper=New Atlas |date=5 June 2020 }}</ref>
== See also ==
{{Portal|Electronics}}
* {{annotated link|Comparison of display technology}}
* {{annotated link|Field-emission display}}
* {{annotated link|Flat-panel display}}
* {{annotated link|Flexible electronics}}
* [[Flexible organic light-emitting diode]]
* [[List of emerging technologies]]
* [[List of flat panel display manufacturers]]
* {{annotated link|Molecular electronics}}
* {{annotated link|Organic light-emitting transistor}}
* {{annotated link|Printed electronics}}
* {{annotated link|Quantum dot display}}
* {{annotated link|Roll-to-roll processing}}
* {{annotated link|Light-on-dark color scheme}} (Dark Mode)
* {{annotated link|Surface-conduction electron-emitter display}}
* [[LED display]]
* [[microLED]]
* [[LED-backlit_LCD#Mini_LED|Mini LED]]
==Notes==
{{notelist}}
==References==
{{reflist}}
== Further reading ==
* T. Tsujimura, ''OLED Display Fundamentals and Applications'', Wiley-SID Series in Display Technology, New York (2017). {{ISBN|978-1-119-18731-8}}.
* P. Chamorro-Posada, J. Martín-Gil, P. Martín-Ramos, L.M. Navas-Gracia, ''Fundamentos de la Tecnología OLED'' (''Fundamentals of OLED Technology''). University of Valladolid, Spain (2008). {{ISBN|978-84-936644-0-4}}. Available online, with permission from the authors, at the webpage: [https://www.scribd.com/doc/13325893/Fundamentos-de-la-Tecnologia-OLED Fundamentos de la Tecnología OLED]
* {{cite journal | last1 = Kordt | first1 = Pascal | display-authors = etal   | year = 2015| title = Modeling of Organic Light Emitting Diodes: From Molecular to Device Properties | journal = Advanced Functional Materials | volume = 25 | issue = 13| pages = 1955–1971 | doi = 10.1002/adfm.201403004 | hdl = 21.11116/0000-0001-6CD1-A | s2cid = 18575622 | hdl-access = free }}
* Shinar, Joseph (Ed.), ''Organic Light-Emitting Devices: A Survey''. NY: Springer-Verlag (2004). {{ISBN|0-387-95343-4}}.
* Hari Singh Nalwa (Ed.), ''Handbook of Luminescence, Display Materials and Devices'', Volume 1–3. American Scientific Publishers, Los Angeles (2003). {{ISBN|1-58883-010-1}}. Volume 1: Organic Light-Emitting Diodes
* Hari Singh Nalwa (Ed.), ''Handbook of Organic Electronics and Photonics'', Volume 1–3. American Scientific Publishers, Los Angeles (2008). {{ISBN|1-58883-095-0}}.
* Müllen, Klaus (Ed.), ''Organic Light Emitting Devices: Synthesis, Properties and Applications''. Wiley-VCH (2006). {{ISBN|3-527-31218-8}}
* Yersin, Hartmut (Ed.), ''Highly Efficient OLEDs with Phosphorescent Materials''. Wiley-VCH (2007). {{ISBN|3-527-40594-1}}
* Kho, Mu-Jeong, Javed, T., Mark, R., Maier, E., and David, C. (2008) 'Final Report: OLED Solid State Lighting – Kodak European Research' MOTI (Management of Technology and Innovation) Project, Judge Business School of the University of Cambridge and Kodak European Research, Final Report presented on 4 March 2008 at Kodak European Research at Cambridge Science Park, Cambridge, UK., pages 1–12.
* {{cite news|url=https://medium.com/@newvisiondisplay/between-cut-throat-competition-which-is-better-oled-lcd-or-pmoled-c611db896cca|title=Between cut-throat competition, Which is better OLED, LCD or PMOLED|first=New Vision|last=Display|newspaper=Medium |date=12 February 2018}}
== External links ==
{{Commons category|OLED}}
* [https://www.lcd-module.com/support/know-how.html OLED, LCD & TFT - Construction and Difference, advantages and disadvantages] {{Webarchive|url=https://web.archive.org/web/20210525145251/https://www.lcd-module.com/support/know-how.html |date=25 May 2021 }} 08. Juli 2020
* [https://www.ewh.ieee.org/soc/cpmt/presentations/cpmt0401a.pdf Structure and working principle of OLEDs and electroluminescent displays]
* [http://techtv.mit.edu/videos/3175 MIT introduction to OLED technology] (video)
* [http://www.oled-info.com/history Historical list of OLED products from 1996 to present]
{{Display technology}}
{{emerging technologies|displays=yes}}
{{Electronic components}}
{{Authority control}}
[[Category:American inventions]]
[[Category:Conductive polymers]]
[[Category:Electronic display devices]]
[[Category:Display technology]]
[[Category:Energy-saving lighting]]
[[Category:Flexible electronics]]
[[Category:Light-emitting diodes]]
[[Category:Molecular electronics]]
[[Category:Optical diodes]]
[[Category:Organic electronics]]