Nearly 100% exciton utilization in highly efficient red OLEDs based on dibenzothioxanthone acceptor

• Published in: Chinese chemical letters Vol. 33; no. 10; pp. 4645 - 4648
• Main Authors: Hu, Xiaoxiao, Qin, Yuanyuan, Li, Zhiyi, Gao, Honglei, Gao, Teng, Liu, Guanhao, Dong, Xiangyu, Tian, Naxi, Gu, Xiuxian, Lee, Chun-Sing, Wang, Pengfei, Wang, Ying
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2022; Key Laboratory of Photochemical Conversion and Optoelectronic Materials and CityU-CAS Joint Laboratory of Functional Materials and Devices,Technical Institute of Physics and Chemistry,Chinese Academy of Sciences,Beijing 100190,China; University of Chinese Academy of Sciences,Beijing 100049,China%Center of Super-Diamond and Advanced Films(COSDAF),City University of Hong Kong,Hong Kong,China
• Subjects: Exciton utilization; Locally excited triplet state; Organic light-emitting diode; Red light; Thermally activated delayed fluorescence; Thermally activated delayed fluorescence; Red light; Organic light-emitting diode; Locally excited triplet state; Exciton utilization
• ISSN: 1001-8417; 1878-5964
• DOI: 10.1016/j.cclet.2021.12.047

Improving the utilization of excitons has always been an important topic for the development of electroluminescence devices. In this work, we designed and synthesized three red TADF emitters TPA-DBT12, TPA-DBT3 and DTPA-DBT by employing dibenzothioxanthone (DBT) acceptor framework to stabilize the locally excited triplet state to participate in the reverse intersystem crossing (RISC) process. The fast RISC process and singlet radiation decay process gave rise to evidently enhanced exciton utilization. All of the red OLEDs based on these materials showed maximum EQE over 11% and high exciton utilization close to 100%. This work not only extend the acceptor framework for red materials but also provide a new perspective for the design of highly efficient red TADF materials with 100% exciton utilization by managing locally excited triplet state.
Constructing thermally activated delayed fluorescence materials based on DBT acceptor to stabilize the locally excited triplet state is demonstrated as a new perspective toward highly efficient red organic light-emitting diodes with 100% exciton utilization. [Display omitted]