Korean team develops next-generation pure green OLED material

On April 14, according to ETnews, a research team from Gyeongsang University in South Korea collaborated with researchers from Samsung Electronics SAIT (formerly Samsung Institute of Technology) and Kyunghee University to develop a new generation of super fluorescent (HF) OLED technology. This technology achieves pure green light emission while achieving ultra-high efficiency and high brightness stability, and is close to the international standard "BT.2020" for wider color gamut and more accurate colors in ultra-high definition (UHD) displays.

In this study, the team designed and synthesized a new multiple resonance-based thermally activated delayed fluorescence (MR-TADF) luminescent material DBF-v-DABNA, and actually applied it to the device, verifying its potential as a core material for next-generation ultra-high-resolution displays.

The next generation of UHD OLED displays not only require high efficiency, but also must simultaneously meet high color purity and high brightness driving stability. BT.2020 is currently the standard that can most accurately reproduce natural colors and has the widest color gamut standard.

To meet this criterion, the luminescence spectrum must remain extremely narrow, so the molecular design of luminescent materials is extremely difficult. Existing green MR-TADF luminescent materials have obvious limitations in achieving high color purity, maintaining efficiency under high brightness, and long device life.

In order to solve these problems, the research team developed a new MR-TADF luminescent material DBF-v-DABNA based on the rigid structure of the molecule center and the three-dimensional design that protects the luminescent part. The material effectively suppresses vibrational coupling, intermolecular interactions, and Dexter energy transfer that lead to reduced efficiency, thereby successfully improving color purity, efficiency, and stability at the same time.

The super fluorescent green OLED using this material has a maximum external quantum efficiency (EQE) of 35.6%. It can still maintain a high efficiency of 33.9% at an actual use level of high brightness of 1000 cd/m2, and achieve a driving life of more than 600 hours at 5000 cd/m2.

Especially in the top-emitting structure where light is emitted in the opposite direction of the substrate, the device reaches a very bright green color of the International Commission on Illumination (CIE) color coordinates (0.14, 0.79), and its performance is very close to the BT.2020 green standard. Through this achievement, the research team proved the feasibility of the next-generation pure green OLED that meets the requirements of high color purity, high efficiency, and high stability.

This research not only developed a new green OLED material, but more importantly, it pointed out the direction of molecular design efforts for next-generation display technology that requires ultra-high color purity, ultra-high efficiency and high stability, which is of great significance.

This research effectively overcomes the long-standing bottleneck of efficiency attenuation and stability of MR-TADF luminescent materials at high brightness, opening up new possibilities for the development of OLED materials for future UHD high-end displays.