Researchers replaced one molecule in an MR-TADF emitter to create the highest-performance emitter to date

Researchers from the South China University of Technology, in collaboration with colleagues from Jihua Laboratory, and Jilin University, have managed to increase the efficiency of deep-blue MR-TADF 5-DABNA OLED emitters, by replacing a single molecule - swapping a phenyl for a tiny methyl group. The researchers say that the new material reached a world-leading 32.48% EQE, and an ultrahigh brightness of 11,619 cd/m².

This one material change made a big difference - the researcher report that it has tripled the reverse intersystem crossing rate (known as kRISC) which improves the light output, while the delayed fluorescence time was shortened by more than half, helping maintain brightness at high power. And the emitter still maintained its 457 nm deep-blue emission with exceptionally narrow (22 nm) spectrum.

The researchers discovered that the methyl group improved performance because it narrowed the energy gap between molecular states, promoting efficient energy transfer and light emission while not affecting the blue color.

In recent years, we have seen increased interest in MR (multiple resonance) TADF OLED emitters research. In May 2025, a group of researchers at Kyushu University, and Soochow University, led by Prof. Chihaya Adachi, have designed a new strategy to develop MR-TADF emitters that offer both a narrowband emission and adequate FMOs energy levels, by manipulating the frontier orbital levels. The researchers explain that the energy level alignment of frontier molecular orbital (FMO) is essential for controlling charge carrier and exciton dynamics in OLED devices.