New blue TADF OLED emitters are as efficient as the best blue PHOLEDs

Researchers from Kyushu University (led by Chihaya Adachi) developed a highly efficient blue OLED TADF (Thermally Activated Delayed Fluorescence) emitter that achieves almost 20% external quantum efficiency - similar to the best blue phosphorescent emitters.

TADF OLEDs are free from the heavy metals used in phosphorescent emitters and so they could be cheaper and better for the environment. The main problem with blue phosphorescent OLEDs is the short lifetime which still makes it impossible to use them in commercial applications. The new TADF blue OLEDs has about the same lifetime as the blue PHOLEDs, but researchers are hopeful that it will be easier to improve the lifetime of the TADF emitters.

The blue TADF emitters also provide a better and more uniform spectral distribution. If TADF emitters are adopted in OLED lighting panels, they may enable OLEDs with a truly continuous spectral distribution. For OLED displays, though, the phosphorescent emitters' sharper spectrum enables a high color purity.

I believe that at the current stage of the industry, lowering the cost of the emitter is not of a prime concern, but if researchers can come up with a long-lasting efficient blue TADF emitter, this can lead to its quick adoption in OLED panels (even though it may mean changes to other materials in the OLED stack).

TADF based OLEDs are also being commercialized by Cynora (based on copper) - and this is not related to the research being performed at Kyushu University. We do not know the efficiency and lifetime of Cynora's blue emitters.

Posted: Mar 30,2014 by Ron Mertens


Fantastic result!