Enhancing Reverse Intersystem Crossing in TSCT-TADF Emitters: Heavy Atom Modulation of Multiresonance Acceptors.

IF 2.7 2区 化学 Q3 CHEMISTRY, PHYSICAL
The Journal of Physical Chemistry A Pub Date : 2025-01-16 Epub Date: 2025-01-03 DOI:10.1021/acs.jpca.4c06357
Jikai Yu, Jia Tang, Zhiying Ma, Hua Wang
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Abstract

With the rapid development of thermally activated delayed fluorescence (TADF) materials, achieving efficient reverse intersystem crossing (RISC) to mitigate triplet-triplet annihilation has emerged as a prominent research focus. This study investigates five derivative molecules, featuring varied bridging atoms/groups (O, S, Se, -CH2-), designed from the reported TADF molecule AC-BO with through-space charge transfer (TSCT) properties. Utilizing time-dependent density functional theory coupled with a PCM solution model, their excited state behaviors were simulated in a toluene environment. Interestingly, it was observed that RISC in AC-BO and one derivative, AC-BCO, occurs predominantly via the T2 state rather than the typical T1 state (3LEB, where B denotes the fluorene bridge), distinguishing it from conventional TSCT-TADF compounds, where RISC typically involves transitions between the 3CT and 1CT states. This distinctive mode is attributed to reduced spin-orbit coupling (SOC) between 1CT and 3LEB, with T2 representing a significant contributor to the RISC process through its 3CT character. Introduction of heavy atoms enhances the electron-withdrawing ability of the acceptor unit, leading to the T1 transitions exhibiting 3MRCT characteristics and increased SOC, thereby favoring RISC via 3MRCT to 1CT transitions. This study not only deepens our understanding of transition mechanisms in TSCT-TADF compounds but also provides crucial insights into the molecular design and regulation of excited triplet states.

增强TSCT-TADF发射体的反向系统间交叉:多共振受体的重原子调制。
随着热激活延迟荧光(TADF)材料的快速发展,实现有效的反向系统间交叉(RISC)以减轻三重态湮灭已成为一个突出的研究热点。本研究研究了五种衍生分子,它们具有不同的桥接原子/基团(O, S, Se, - ch2 -),由报道的具有通过空间电荷转移(TSCT)性质的TADF分子AC-BO设计而成。利用时变密度泛函理论和PCM溶液模型,模拟了它们在甲苯环境中的激发态行为。有趣的是,我们观察到AC-BO及其衍生物AC-BCO中的RISC主要通过T2态而不是典型的T1态(3LEB,其中B表示芴桥)发生,这与传统的TSCT-TADF化合物不同,后者的RISC通常涉及3CT和1CT态之间的转变。这种独特的模式归因于1CT和3LEB之间减少的自旋轨道耦合(SOC), T2通过其3CT特性代表了RISC过程的重要贡献者。引入重原子增强了受体单元的吸电子能力,导致T1跃迁表现出3MRCT特征,并增加了SOC,从而有利于通过3MRCT向1CT跃迁的RISC。这项研究不仅加深了我们对TSCT-TADF化合物过渡机制的理解,而且为激发态的分子设计和调控提供了重要的见解。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
The Journal of Physical Chemistry A
The Journal of Physical Chemistry A 化学-物理:原子、分子和化学物理
CiteScore
5.20
自引率
10.30%
发文量
922
审稿时长
1.3 months
期刊介绍: The Journal of Physical Chemistry A is devoted to reporting new and original experimental and theoretical basic research of interest to physical chemists, biophysical chemists, and chemical physicists.
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