Heavy-atom effect promotes multi-resonance thermally activated delayed fluorescence
Heavy-atom effect promotes multi-resonance thermally activated delayed fluorescence
复制标题
重原子效应促进多共振热激活延迟荧光
DOI：
10.1016/j.cej.2021.131169
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发表时间：
2021-07-17
影响因子：
15.1
通讯作者：
Yang, Chuluo
中科院分区：
文献类型：
--
作者：
Hua, Tao;Zhan, Lisi;Yang, Chuluo
作为一种同时具有高效率和颜色纯度的最新发射器，多共振热激活延迟荧光（MR-TADF）材料的开发代表了有机发光二极管（OLED）的重要进步。我们提出了一种通过将硫元素熔合到B-N基框架中来提高MR-TADF发射器性能的新策略，旨在利用非金属重原子效应加速发射器的反向系间窜越（RISC）过程。这项工作通过硫或氧原子刚性化 DABNA-1 骨架，开发了两种化合物，即 2PTZBN 和 2PXZBN。理论计算和光致发光研究表明，与2PXZBN相比，掺硫的2PTZBN由于自旋轨道耦合（SOC）值更大和更小的单重态-三重态能量分裂（Delta EST），在甲苯中能够实现高达2.8 x 10(5) s(-1)的相当大的RISC（kRISC）速率常数。因此，基于2PTZBN的有机发光二极管表现出高效的绿色发射，最大外量子效率（EQE）为25.5%。
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 (kRISC) up to 2.8 x 10(5) s(-1) in toluene due to larger spin-orbital coupling (SOC) values and smaller singlet-triplet energy splitting (Delta EST) 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%.