Tailoring Donor-Acceptor Emitters to Minimise Localisation Induced Quenching of Thermally Activated Delayed Fluorescence
Tailoring Donor-Acceptor Emitters to Minimise Localisation Induced Quenching of Thermally Activated Delayed Fluorescence
复制标题
定制供体-受体发射体以最大限度地减少热激活延迟荧光的局域诱导猝灭
DOI：
10.1002/cptc.202200243
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发表时间：
2022
期刊：
影响因子：
3.7
通讯作者：
Penfold T
中科院分区：
文献类型：
--
作者：
Penfold T
通过将热激活延迟荧光 (TADF) 材料的常见结构基序反转为刚性供体核心和多个外围受体，已证明可以实现反向系间窜越 (rISC) 速率 1×107s−1 和单位光致发光量子产率 [Dos Santoset al.副词。科学5（2018）1700989]。然而，该基序中的 rISC 速率因激发态电子结构的局部化而被猝灭，这导致外围受体之间的不等价。在本文中，我们探索了一系列相关的分子靶标，旨在减少定位对 rISC 率的影响。这包括含有呈现三重或四重对称性的供体的结构，以及供体-受体键周围不同程度的空间位阻，目的是利用空间位阻对激发态动力学进行更精细的构象控制，以增强功能特性。我们证明，由于局部激发态的能量位置，三氮杂苯中心供体对 TADF 最有效，而氰基苯甲腈是减少局域化对电子结构影响的最有效受体。这些还将发射推入光谱的蓝色区域，从而为开发高效蓝色 TADF 发射器开辟了道路。
By inverting the common structural motif of thermally activated delayed fluorescence (TADF) materials to a rigid donor core and multiple peripheral acceptors, it has been shown possible to achieve both a reverse intersystem crossing (rISC) rate 1×107s−1and a unity photoluminescence quantum yield [Dos Santoset al. Adv. Sci.5(2018) 1700989]. However, the rISC rate in this motif is quenched by localisation of the excited state electronic structure which causes in‐equivalence between the peripheral acceptors. In this paper, we explore a series of related molecular targets which seek to reduce the effect of localisation on the rISC rates. This includes structures that contain donors exhibiting three‐fold or four‐fold symmetry and different degrees of steric hindrance around the donor‐acceptor bond with the objective of using steric hindrance to exert finer conformational control of the excited state dynamics to enhance functional properties. We demonstrate that a triazatruxene central donor is most effective for TADF owing to the energetic position of the locally excited state, while cyano‐benzonitriles are the most effective acceptors for reducing the effect of localisation on the electronic structure. These also push the emission into the blue region of the spectrum, opening the possibilities for this to be a pathway to develop efficient blue TADF emitters.