Fluorescent

Researchers from Seoul National University (SNU), in collaboration from colleagues from Samsung's SAIT institute, have identified a critical mechanism behind the performance degradation of OLED devices, the interfacial exciton-polaron quenching mechanism.

The researches have theoretically proposed a mechanism where excitons in the light-emitting layer are quenched by the accumulated charges at the interface. They followed with with experiments that have independently observed this phenomenon, identifying three key factors: interfacial barrier, exciton-polaron distance, and exciton lifetime. 

A report from Korea says that LG Display has successfully developed an OLED panel that is based on a blue phosphorescence emitter. The blue PHOLED, provided by Universal Display, offers 100% IQE, up from 25% used by current fluorescence emitters. This will result in around 20-30% power saving for the display itself (depending on the images shown).

UDC has been developing blue emitters for many years, and recently the company said that the development will take a few more months and won't be ready in 2024. The main challenge is increasing the lifetime of the materials. However LG Display has adopted a tandem design to enable a commercially ready display, perhaps even sooner than UDC planned.

Researchers from the Tokyo Institute of Technology, Osaka University, University of Toyama and Shizuoka University have developed a fluorescent blue (462 nm) OLED device that features an ulta-low turn-on voltage of 1.47 V (at 100 nits). The researchers say this is very low, as similar commercial blue devices typically need around 4 V.

To achieve that low turn-on voltage, the researchers built a new device, as they realize that the choice of materials significantly influences the device's turn-on voltage. The device itself is an upconversion OLED.

Researchers from the University of Manchester, led by Prof. Alexander Romanov, developed a promising new Carbene-Gold-Arylacetylide (CMAc) OLED near UV emitter type. The researchers also detail a strategy to develop longer device lifetimes for such emitters.

The new emitter exhibits an efficiency of 1% EQE, and a lifetime of 20 minutes at a practical brightness of 10 nits (LT50). This is low compared to commercial OLEDs - but it is actually quite outstanding for such an emitter, and the researchers say that this is among the longest lifetimes for a near UV-OLED at a practical brightness ever reported. In addition, organic fluorescent and TADF emitters rarely exceed 1% EQE at practical brightness.

This is a sponsored post by Nanomatch

Using their in-house virtual design tools, Nanomatch developed a new class of emitters that enables the production of stable, fluorescent OLED devices with close to 100% internal quantum efficiency also in the blue color range.

The specific class of fluorescent emitters facilitates the generation of only singlets with radiative decay of the order of 10-8s, thereby eliminating quenching processes induced by long-lived triplets. Having filed the patent end of February 2023, Nanomatch is now looking for partners to commercialize this new concept in order to realize efficient, stable blue OLEDs on an industrial level.

Researchers from Kyushu University reported that they have developed a promising new blue OLED emitter system, based on a two-unit stacked tandem hyperfluorescence OLED with improved singlet-excited-state energy transfer from a sky-blue assistant hetero-donor-type TADF (HDT-1) dopant.

The research reports that the new emitter system offers a pure-blue color (CIE 0.13, 0.16), a narrow spectrum (full-width at half-maximum of 19 nm), an EQE of 32% at 1,000 cd/m² and a lifetime of 18 hours LT95. The lifetime is still lacking, but with stricter control of device fabrication and procedures the researchers say they expect that device lifetimes will further improve to rival commercial fluorescent blue OLEDs.

Kyulux presented a new paper at SID Displayweek, that shows the latest progress of the company's Hyperfluorescence OLED emitter platform. You can see the latest performance chart below.

Hyperfluorescence combines TADF and fluorescence emitters, which enables high-efficiency (~100% IQE) emitters that feature long lifetimes and a very narrow emission spectrum. The company's yellow HF emitter is already commercialized, and now Kyulux says that its red and green materials are "close to commercialization". The company is also improving the color point and lifetime of its HF blue emitters.

Amber Molecular announced that it has completed its Series A funding round, raising $5 million USD, led by Phoenix Venture Partners.

Amber Molecular was established in 2017 by researchers at The University of Toronto in Canada to develop novel fluorescent OLED emitters. Amber Molecular's patented family of fluorescent OLED emissive materials produce photons in the orange, red and infrared spectrum, targeting new OLED applications.

WiseChip Semiconductor, based in Taiwan, is one of the world's leading PMOLED maker (in fact in 2015 Wisechip said it's the world's second largest). Wisechip is developing next-generation PMOLED displays, including flexible panels, transparent panels and Hyperfluorescence/TADF PMOLEDs.

WiseChip recently announced its first, and the world’s first, Hyperfluorescence display, using TADF materials provided by Kyulux. Can you tell some more about this display and its properties?

This 2.70 128x64 product is adopted mostly in industrial products. The size matters in such market but the main problem was to increase the brightness due to the limited efficiency of the fluorescence emitters. The Hyperfluorescence technology helps to settle the problem and can reach up 2.5 times brighter. It performs much better readability so users do not have to stand right in front of the device. This feature adds to the value of the end product.