title: Optimizing Optoelectronic Properties of Pyrimidine-Based TADF Emitters by Changing the Substituent for Organic Light-Emitting Diodes with External Quantum Efficiency Close to 25 % and Slow Efficiency Roll-Off.
abstract: A series of green butterfly-shaped thermally activated delayed fluorescence (TADF) emitters, namely PXZPM, PXZMePM, and PXZPhPM, are developed by integrating an electron-donor (D) phenoxazine unit and electron-acceptor (A) 2-substituted pyrimidine moiety into one molecule via a phenyl-bridge π linkage to form a D-π-A-π-D configuration. Changing the substituent at pyrimidine unit in these emitters can finely tune their emissive characteristics, thermal properties, and energy gaps between the singlet and triplet states while maintaining frontier molecular orbital levels, and thereby optimizing their optoelectronic properties. Employing these TADF emitters results in a green fluorescent organic light-emitting diode (OLED) that exhibits a peak forward-viewing external quantum efficiency (EQE) close to 25 % and a slow efficiency roll-off characteristic at high luminance.
authors.affiliation: Hubei Collaborative Innovation Center for Advanced, Organic Chemical Materials, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, 430072, People's Republic of China.
authors.forename: Kailong
authors.initials: K
authors.lastname: Wu
authors.affiliation: Yunnan Key Laboratory for Micro/Nano Materials and Technology, Department of Physics, Yunnan University, Kunming, 650091, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Hubei Collaborative Innovation Center for Advanced, Organic Chemical Materials, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, 430072, People's Republic of China.
authors.forename: Lisi
authors.initials: L
authors.lastname: Zhan
authors.affiliation: Hubei Collaborative Innovation Center for Advanced, Organic Chemical Materials, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, 430072, People's Republic of China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhong
authors.affiliation: Hubei Collaborative Innovation Center for Advanced, Organic Chemical Materials, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, 430072, People's Republic of China. slgong@whu.edu.cn.
authors.forename: Shaolong
authors.initials: S
authors.lastname: Gong
authors.affiliation: Yunnan Key Laboratory for Micro/Nano Materials and Technology, Department of Physics, Yunnan University, Kunming, 650091, People's Republic of China. jiangnan@ynu.edu.cn.
authors.forename: Nan
authors.initials: N
authors.lastname: Jiang
authors.affiliation: Yunnan Key Laboratory for Micro/Nano Materials and Technology, Department of Physics, Yunnan University, Kunming, 650091, People's Republic of China.
authors.forename: Zheng-Hong
authors.initials: ZH
authors.lastname: Lu
authors.affiliation: Hubei Collaborative Innovation Center for Advanced, Organic Chemical Materials, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, 430072, People's Republic of China. clyang@whu.edu.cn.
authors.forename: Chuluo
authors.initials: C
authors.lastname: Yang
keywords: emitters; optoelectronics; organic light-emitting diodes; pyrimidine derivatives; thermally activated delayed fluorescence