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Is TADF the future of efficient OLED emitters?

Nov 02, 2016
This is a premium OLED-Info article

TADF, or Thermally Activated Delayed Fluorescence, represents a class of OLED emitter materials that aim to provide efficient and long-lifetime performance. TADF research started in earnest in 2012, and some believe that TADF represent an exciting new platform for next-gen OLED emitters.

Blue TADF emitter molecules

As OLED display adoption grows, researchers and developers at Universities and companies are looking to develop more efficient and cost-effective OLED materials. There are currently three main drivers for these efforts - the development of an efficient and long-lasting blue color emitter, the development of alternative non-phosphorescent emitters and the development of soluble materials that can be deposited in ink-jet printing and other "wet" methods.

Cynora latest TADF blue emitters feature higher efficiency and lifetime

Oct 05, 2016

Germany-based blue-TADF OLED emitter developer Cynora announced that it developed a new blue-emitting material that combines high efficiency with long lifetime. Cynora's new material offers an external quantum efficiency (EQE) of 14% and a lifetime of 420 hours (LT80, at 500 cd/m2).

Cynora blue TADF emitter photo

In May 2016 Cynora announced two blue emitter systems - with one featuring a high efficiency and the other a long lifetime. This time Cynora managed to create a single system with both efficiency and lifetime. The company says that they are optimistic that they will reach a commercial TADF blue emitter by the end of 2017.

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Will SEL's ExTEF device architecture finally enable an efficient blue OLED?

Aug 26, 2016

Researchers from Japan's Semiconductor Energy Laboratory (SEL) developed a new OLED device architecture that enables efficient, long-lasting and low-drive voltage OLEDs, at practical brightness levels.

ExTET process and energy states diagram

The researchers call the new device architecture exciplex-triplet energy transfer, or ExTEF. The image above shows the elementary process and its energy state diagram. To create the emissive layer of the ExTEF, the researcher took a film with an electron-transporting material (ETM) and a hole-transporting material (HTM) and doped it with a phosphorescent dopant. Direct recombination between the electrons at the LUMO level and the hole at the HUMO level forms a charge-transfer excited complex (exciplex) - and the phosphorescent emission occurs via energy transfer from the exciplex to the dopant.

Researchers develop a new tool to quickly identify new OLED molecules

Aug 09, 2016

Researchers from Harvard University, MIT and Samsung developed a large-scale computer-driven material screening process that incorporates theoretical and experimental chemistry, machine learning and cheminformatics, with an aim to quickly identify new OLED molecules.

The so-called Molecular Space Shuttle system was used to design more than 1,000 new high-performance blue-light emitting molecules. It seems that there is still a lot of work ahead to find the best new candidates and actually test these molecules, but this may be a promising new direction in OLED molecule research.

Kyulux: advancing fast to commercialize yellow, green and blue TADF emitters

Jun 28, 2016

Kyulux logoIn early 2016, Kyushu University in Japan spun-off a new start-up called Kyulux to commercialize the TADF emitters developed at the University. A few months later, Kyulux raised $13.5 million (from LG, Samsung, Japan Display and JOLED).

We have met with Kyulux's team at SID 2016, who updated us that the company is progressing fast on the way to commercialize those TADF emitters. The first products to be ready are green and yellow emitters. Kyulux says that its Hyper-fluorescence TADF emitters offer a superior performance compared to PHOLED emitters (in both intensity and color purity) - and they should also be priced lower - so the company aims to provide a viable alternative to UDC's emitters in the near future.

OLEDWorks to investigate novel blue OLED materials with support from the DoE

May 17, 2016

The US Department of Energy (DOE) announced 13 new grants for building technology projects that promise to boost the efficiency of buildings.

OLEDWorks at L+B 2016

One of those projects was granted to OLEDWorks, which will investigate novel blue OLED materials. The DoE did not give any more details for this project, but it did say that the award amount of each project was up to $150,000.

Cynora announces significant progress towards highly-efficient blue OLED emitters

May 04, 2016

Germany-based OLED emitter developer Cynora announced it has made significant progress in its highly efficient blue OLED emitter material developments during the last 6 months. The company's materials are not yet ready for commercialization, but the company believes it is on its way.

Cynora blue TADF emitter photo

Cynora develops TADF-based emitters, focusing on blue-color emitters. Cynora has developed deep blue material reaching an EQE of 16.3% (at 100 cd/m2) compared to 3% reached in October 2015, a factor 5 improvement in six months.

An interview with Idemitsu Kosan's electronic material's chief

Jan 05, 2016

Hajime Nakamoto (Idemitsu Kosan)Idemitsu Kosan is a large multinational Chemical company based in Japan that is supplying OLED materials for OLED producers. Idemitsu has OLED business units in Japan, Taiwan, Korea and China and is collaborating with UDC, LGD, AU Optronics, Doosan and others.

Hajime Nakamoto, the head of the Electronic Materials Department at Idemitsu was kind enough to answer a few questions we had. Mr. Nakamoto joined Idemitsu in 1984 and has been involved with OLEDs since 2007.

Q: Hajime, Thank you for your time. Idemitsu has been one of the leaders in OLED materials for a very long time. Can you tell us what kind of materials you currently offer for OLED panel makers?

Idemitsu offers almost all kinds of OLED materials to OLED panel makers. Idemitsu is particularly well-known for its fluorescent blue host and dopant materials and transport materials, which offer advantages to OLED panel makers.

ITRI developed a highly efficient blue OLED emitter based on plasmon-coupled green PHOLED

Nov 26, 2015

Taiwan's ITRI research institute developed a long-lasting OLED blue emitter. The researchers used a green phosphorescent emitter with a new double metal structure - that emits a blue light. The so-called Plasmon-Coupled Organic Light Emitting Diode (PCOLED) structure's lasts 27 times as long as a blue fluorescent emitter.

ITRI PCOLED diagram

The researchers explain that a regular green phosphorescent emitter always emits a very weak emission. By using the double-metal structure, more plasmons are generated which means a larger blue emission. This is not an up-conversion process - but merely a change in conditions within the green material. This condition was actually discovered by accident.

Researchers develop an efficient deep-blue PHOLED

Oct 21, 2015

Researchers at the University of Michigan developed a new deep-blue energy-efficient phosphorescent OLED (PHOLED) emitter. The researchers say that this is the brightest deep-blue PHOLED ever reported - in fact it is about 10 times brighter than previous deep-blue PHOLEDs. The lifetime of this material is still very low, and future research will attempt to stabilize the molecule.

Bright blue PHOLED (University of Michigan)

The new emitter is based on a N-heterocyclic carbene iridium-III complex molecule. This is an efficient compound because its design reduces the chances that light-emitting excitons will either get lost as heat or destroy the compound itself. This research is sponsored by Universal Display Corporation and the U.S. Air Force.