TADF, or Thermally Activated Delayed Fluorescence, is a relatively new class of OLED emitter materials that promise efficient and long-lifetime performance without any heavy metals. TADF research started in earnest in 2012, and the first TADF emitters reached commercial status at the end of 2019.
There are currently three main challenges with OLED emitters that TADF aims to solve - an efficient and long-lasting blue color emitter, low cost alternatives current red and green emitters and the development of soluble OLEDs that can be deposited using low cost ink-jet printing or other "wet" methods.
TADF is being developed by several companies. Japan-based Kyulux was established to commercialize Prof. Adachi's HyperFluoresence TADF technology. Germany-based Cynora is focusing on a blue TADF emitter. Both companies are working hard to achieve commercial-ready materials. While a blue TADF (or HF) emitter is not here yet, in late 2019 Kyulux and Wisechip brought to market the first OLED with a yellow HF emitter.
Idemitsu Kosan also considers TADF as one of the key OLED technologies and intends to focus on TADF in the future. In late 2019 Idemitsu together with Toray announced the world's most efficient red OLED emitter - based on Idemitsu's TADF/HF material. UDC has been recently awarded a patent on TADF materials, although the company says that TADF is not in its focus.
The latest TADF news:
Researchers from the University of Cambridge and Jilin University discovered that radical-based OLEDs feature highly efficient emission - in fact they believe that this discovery could be an elegant solution to the problem of in-efficient OLED emission.
First-generation OLED emitters (fluorescent emitters) have a maximum internal quantum efficiency of 25% - as only a quarter of the electrons are in a singlet-state (that emit light) while 75% of the electrons are in a triplet-state. Current ways to achieve 100% IQE are either based on doping with heavy metals (phosphorescent emission) or either based on delayed fluorescence (TADF).
TADF developer CYNORA has announced that it has extended its joint-development agreement with LG Display. The two companies have been co-developing deep-blue TADF OLED emitters for two years, and have now decided to continue the cooperation towards the commercialization of TADF emitters in OLED displays.
CYNORA's latest deep-blue material specification was presented in May 2018 - with a CIEy of 0.14, EQE of 20% and a lifetime of 20 hours LT97 at 700 nits. Cynora expects to have blue material in mass production by 2020. Cynora says that its TADF materials are suitable for both self-emitting or co-emitting approaches (which includes hyper-fluorescence).
DSCC estimates that Samsung will begin pilot production of QD-OLEDs in 2019, with a capacity of 5,000 monthly 8.5-Gen substrates. If this is successful, Samsung will double the capacity in 2020 and add a further 30,000 yearly substrates in 2021 and again in 2022. Material revenues for Samsung's QD-OLED TVs will reach $56 million in 2022.
DSCC admits, though, that as Samsung faces several technical challenges before it could launch commercial QD-OLED TVs, its forecast could be way off - there's a good chance that SDC will cancel the project, or it could increase capacity at a much faster rate than DSCC estimates and even scale-up production to 10.5-Gen.
CYNORA's latest material specification was presented in May 2018 - with a CIEy of 0.14, EQE of 20% and a lifetime of 20 hours LT97 at 700 nits. Cynora expects to have blue material in mass production by 2020, and when its deep-blue material is ready it will start to develop the less challenging highly efficient green and red materials. Last month we interviewed Cynora's CMO Dr. Andreas Haldi - who talked about TADF, lifetime, color points and more.
Kyulux signs JDA agreements with both SDC and LGD - aims to have commercial ready TADF/HF emitters ready by mid 2019
Kyulux announced that it has signed joint-development agreements (JDAs) with both LG Display and Samsung Display. The LGD agreement was signed in January 2018 while the SDC one was recently signed. Both agreements focus on deep blue Hyperfluoresence / TADF emitters.
Kyulux hopes that by collaborating with the two leading OLED producers, it will be able to accelerate its material development - and it aims to have commercial red, green and blue HF/TADF emitters ready by mid 2019.
An interview with Cynora's CMO Dr. Andreas Haldi - talking about TADF, lifetime, color points and more
German TADF developer Cynora presented its latest blue TADF material in May 2018 - with a CIEy of 0.14, EQE of 20% and a lifetime of 20 hours LT97 at 700 nits. Cynora expects to have blue material in the mass production by 2020.
Cynora's Chief Marketing Offer, Dr. Andreas Haldi was kind enough to answer a few questions we had regarding TADF emitters, the differences between next-generation emitter technologies, lifetime, color points and more.
Kyulux announced that it has developed a new blue Hyperfluoresence/TADF OLED emitter. Kyulux managed to extend the lifetime of the material and reached 100 hours at LT95 (@ 750 cd/m2) while maintaining a high EQE of 26% - 22% at 1,000 cd/m2. The emission wavelength is 470 nm.
Kyulux says that its blue Hyperfluorescence emitter is the world’s top performing material at the moment. Kyulux now aims to work together with OLED panel makers to improve the systems further by optimizing the device structure and the rest of the OLED stack in pilot production lines.
Kyulux and Wisechip unveiled a flexible PMOLED display that uses Kyulux’s Hyperfluoresence yellow emitter. Wisechip says that the power consumption of this display is almost half of Wisechip's regular fluorescent yellow PMOLED.
The first flexible HF PMOLED is a 1.71″ 256x64 display, that is now ready to be produced (Wisechip says this will enter mass production before the end of 2018). Wisechip originally aimed to introduce its first glass-based HF yellow emitter PMOLED by the end of 2017, but it seems they decided to jump straight to a flexible panel.
Researchers from the Universitat Autònoma de Barcelona and TU-Dresden have demonstrated that ultra-stable film formation can be used to to improve the performance of OLED devices.
The researchers grew (using evaporation) the organic materials as ultrastable glasses - a growth condition that allows for thermodynamically most stable amorphous solids. Testing four different phosphorescent emitters, the researchers show significant (over 15%) increases of efficiency and operational stability. The researchers also say that these growing conditions are expected to even be more useful for TADF materials.
Thermal activation sensitized fluorescence, or TASF, is a new type of TADF OLED emitter material developed at China's Tsinghua University. During SID Displayweek, Visionox demonstrated the first TASF prototype display.
We do not have a lot of information on this new emitter technology, except what Visionox provided at the conference: a sky-blue color (468 nm, CIE: 0.153, 0.201), a luminous efficiency of 26.6 cd/A and an external quantum efficiency of over 17%. The brightness of this OLED PMOLED display was 800 nits.