文献类型：期刊文献

英文题名：Triangle-Free Inverted Singlet–Triplet Emitters with a Record Fast Delayed Lifespan for Efficient and Low Efficiency Roll-Off Organic Light-Emitting Diodes

作者：Lü, Zhaoyue[1]; Chai, Tiantian[2]; Jin, Yichao[1]; Wang, Xiao[1]; Zhang, Lijiang[1]; Feng, Jiankang[2]; Zhang, Mengtong[2]; Wang, Shuo[2]; Lu, Chichong[3]; Jin, Guofan[2]

机构：[1] School of Physics, East China University of Science and Technology, Shanghai, 200237, China; [2] School of Pharmacy, Jiangsu University, Zhenjiang, 212013, China; [3] College of Chemistry and Materials Engineering, Beijing Technology and Business University, Beijing, 100048, China

年份：2024

外文期刊名：SSRN

收录：EI(收录号：20240209553)

语种：英文

外文关键词：Charge transfer - Fluorescence - Luminance - Organic light emitting diodes (OLED)

摘要：A couple of inverted singlet-triplet gap (?0.13 eV) emitters are created by alternating donor and acceptor groups at the molecular edge. The excited-state energy inversion may be explained by both spatially separated frontier orbitals and double excitations. The double excitations are likely caused by the formation of localized and delocalized charge transfer (CT) states. Additionally, a record short delayed lifespan of around 100 ns is noted, which may be attributed to both down-conversion process without thermal activation and the strong spin-orbital coupling between the lowest singlet CT and the lowest triplet localized excited states. High-performance OLEDs with the highest external quantum efficiencies of 13% and 9.1% are demonstrated using the two emitters. Remarkably, the devices sufficiently maintain high efficiency at (ultra-) high luminance, 96% and 67% of the maximum EQE at 1 000 cd/m2 and 10 000 cd/m2 for the green emitter, and 87% and 54% for the sky-blue emitter. This might be ascribed to the suppression of exciton quenching by substantially shortening the delayed lifespan. These findings illustrate the practicality of the molecular design motif of a molecular periphery with alternating donor and acceptor groups for the inverted singlet-triplet emitters and their potentials for high performance OLEDs. ? 2024, The Authors. All rights reserved.