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Heavy-atom effect promotes multi-resonance thermally activated delayed fluorescence.

Authors :
Hua, Tao
Zhan, Lisi
Li, Nengquan
Huang, Zhongyan
Cao, Xiaosong
Xiao, Zhengqi
Gong, Shaolong
Zhou, Changjiang
Zhong, Cheng
Yang, Chuluo
Source :
Chemical Engineering Journal. Dec2021, Vol. 426, pN.PAG-N.PAG. 1p.
Publication Year :
2021

Abstract

[Display omitted] • Narrowband green emitters are successfully achieved by multi-resonance boron-nitrogen framework. • Heavy-atom effect of sulfur was beneficial to accelerate the reverse intersystem crossing. • Green organic light-emitting diodes with high external quantum efficiency up to 25.5% are achieved. As one type of latest emitters with simultaneous high efficiency and color-purity, the development of multi-resonance thermally activated delayed fluorescence (MR-TADF) materials represents an important advancement for organic light-emitting diodes (OLEDs). We herein present a new strategy to improve the performance of MR-TADF emitters by fusing sulfur element into the B-N based framework, aiming to utilize the non-metal heavy-atom effect in accelerating the reverse intersystem crossing (RISC) process of the emitter. Two compounds, namely 2PTZBN and 2PXZBN, were developed in this work through rigidifying the DABNA-1 skeleton by sulfur or oxygen atoms. The theoretical calculations and photoluminescence studies reveal that the sulfur-incorporated 2PTZBN enable considerable rate constant of RISC (k RISC) up to 2.8 × 105 s−1 in toluene due to larger spin-orbital coupling (SOC) values and smaller singlet–triplet energy splitting (Δ E ST) compared with 2PXZBN. Consequently, organic light-emitting diodes based on 2PTZBN exhibited highly efficient green emission with maximum external quantum efficiency (EQE) of 25.5%. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
13858947
Volume :
426
Database :
Academic Search Index
Journal :
Chemical Engineering Journal
Publication Type :
Academic Journal
Accession number :
153371333
Full Text :
https://doi.org/10.1016/j.cej.2021.131169