TY - JOUR
T1 - Managing Locally Excited and Charge-Transfer Triplet States to Facilitate Up-Conversion in Red TADF Emitters That Are Available for Both Vacuum- and Solution-Processes
AU - Chen, Jia-Xiong
AU - Xiao, Ya-Fang
AU - Wang, Kai
AU - Sun, Dianming
AU - Fan, Xiao-Chun
AU - Zhang, Xiang
AU - Zhang, Ming
AU - Shi, Yi-Zhong
AU - Yu, Jia
AU - Geng, Feng-Xia
AU - Lee, Chun-Sing
AU - Zhang, Xiao-Hong
PY - 2021/2/1
Y1 - 2021/2/1
N2 - Developing red thermally activated delayed fluorescence (TADF) emitters for high-performance OLEDs is still facing great challenge. Herein, three red TADF emitters, pDBBPZ-DPXZ, pDTBPZ-DPXZ, and oDTBPZ-DPXZ, are designed and synthesized with same donor–acceptor (D-A) backbone with different peripheral groups attaching on the A moieties. Their lowest triplet states change from locally excited to charge transfer character leading to significantly enhance reverse intersystem crossing process. In particular, oDTBPZ-DPXZ exhibits efficient TADF feature and exciton utilization. It not only achieves an external quantum efficiency (EQE) of 20.1 % in red vacuum-processed OLED, but also realize a high EQE of 18.5 % in a solution-processed OLED, which is among the best results in solution-processed red TADF OLEDs. This work provides an effective strategy for designing red TADF molecules by managing energy level alignments to facilitate the up-conversion process and thus enhance exciton harvesting.
AB - Developing red thermally activated delayed fluorescence (TADF) emitters for high-performance OLEDs is still facing great challenge. Herein, three red TADF emitters, pDBBPZ-DPXZ, pDTBPZ-DPXZ, and oDTBPZ-DPXZ, are designed and synthesized with same donor–acceptor (D-A) backbone with different peripheral groups attaching on the A moieties. Their lowest triplet states change from locally excited to charge transfer character leading to significantly enhance reverse intersystem crossing process. In particular, oDTBPZ-DPXZ exhibits efficient TADF feature and exciton utilization. It not only achieves an external quantum efficiency (EQE) of 20.1 % in red vacuum-processed OLED, but also realize a high EQE of 18.5 % in a solution-processed OLED, which is among the best results in solution-processed red TADF OLEDs. This work provides an effective strategy for designing red TADF molecules by managing energy level alignments to facilitate the up-conversion process and thus enhance exciton harvesting.
KW - charge-transfer triplet state
KW - locally excited triplet state
KW - solution-processed OLED
KW - thermally activated delayed fluorescence
KW - vacuum-deposited OLED
KW - charge-transfer triplet state
KW - locally excited triplet state
KW - solution-processed OLED
KW - thermally activated delayed fluorescence
KW - vacuum-deposited OLED
KW - charge-transfer triplet state
KW - locally excited triplet state
KW - solution-processed OLED
KW - thermally activated delayed fluorescence
KW - vacuum-deposited OLED
UR - http://www.scopus.com/inward/record.url?scp=85096675920&partnerID=8YFLogxK
UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-85096675920&origin=recordpage
U2 - 10.1002/anie.202012070
DO - 10.1002/anie.202012070
M3 - RGC 21 - Publication in refereed journal
SN - 1433-7851
VL - 60
SP - 2478
EP - 2484
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
IS - 5
ER -