Proof of the mechanism accelerating the degradation of charge separation paper

Researchers from Samsung Electronics' Advanced Institute of Technology and a research team led by Professor Yoo Young-min of the Department of Chemical and Materials Engineering at Ewha Womans University have for the first time demonstrated the degradation mechanism causing the lifespan reduction of OLED blue phosphorescent materials and proposed a material design method to improve this.

If this technology is commercialized, it will be possible to 혁신적으로 extend the lifespan and performance of OLEDs, which currently use fluorescent materials for only the blue light among the three primary colors of red, green, and blue emission, rather than phosphorescent materials.

OLEDs are self-emissive organic compounds that offer the advantages of a bright screen, excellent contrast ratio, and low power consumption. However, unlike red and green, where high-efficiency phosphorescent materials have already been commercialized, blue phosphorescence has not been commercialized due to its short lifespan, so fluorescent materials are currently used; consequently, it has been pointed out that they are not suitable for long-term use exceeding several years.

While analyzing the material degradation pathway of blue phosphorescence, the research team identified a mechanism in which charge-separating species formed during the electronic transfer process between phosphorescent components accelerate degradation. This is the first study to scientifically prove why the lifespan of blue phosphorescent materials shortens so much faster than that of red and green materials.

Furthermore, the research team confirmed that lifespan differences of up to tens of times occur depending on the extinction rate of charge separation species, and proposed a material combination structure capable of extending lifespan by eliminating charge separation species as quickly as possible.

"The ultimate goal is to find a blue phosphorescent material capable of minimizing degradation through further research and apply it to actual systems," said In Su-kang, a principal researcher at the Advanced Institute of Technology who participated in this joint study. "Professor Yoo Young-min of Ewha Womans University said, 'This study is significant in that it presents a new chemical mechanism explaining the cause of the short lifespan of blue OLED devices, and this mechanism could be usefully applied to understanding the lifespan of other electronic devices, such as organic transistors.'"