Bright, efficient, and stable pure-green hyperfluorescent organic light-emitting diodes by judicious molecular design
Yi‐Ting Lee, Chin‐Yiu Chan, N. Matsuno, Shigetada Uemura, Susumu Oda, Masakazu Kondo, Rangani Wathsala Weerasinghe, Yanmei Hu, Gerardus N. Iswara Lestanto, Youichi Tsuchiya, Yufang Li, Takuji Hatakeyama, Chihaya Adachi
Abstract
Abstract To fulfill ultra-high-definition display, efficient and bright green organic light-emitting diodes with Commission Internationale de l’Éclairage y-coordinate ≥ 0.7 are required. Although there are some preceding reports of highly efficient devices based on pure-green multi-resonance emitters, the efficiency rolloff and device stabilities for those pure-green devices are still unsatisfactory. Herein, we report the rational design of two pure-green multi-resonance emitters for achieving highly stable and efficient pure-green devices with CIE x,y s that are close to the NTSC and BT. 2020 standards. In this study, our thermally activated delayed fluorescence OLEDs based on two pure-green multi-resonance emitters result in CIE y up to 0.74. In hyperfluorescent device architecture, the CIE x s further meet the x-coordinate requirements, i.e., NTSC (0.21) and BT. 2020 (0.17), while keeping their CIE y s ~ 0.7. Most importantly, hyperfluorescent devices display the high maximum external quantum efficiencies of over 25% and maximum luminance of over 10 5 cd m −2 with suppressed rolloffs (external quantum efficiency of ~20% at 10 4 cd m −2 ) and long device stabilities with LT 95 s of ~ 600 h.