Supplementary information files for "Elucidating the non-radiative losses encountered in intramolecular charge transfer compounds with benzodithiophene-4,8-dione acceptors"

Supplementary files for article "Elucidating the non-radiative losses encountered in intramolecular charge transfer compounds with benzodithiophene-4,8-dione acceptors"A new yellow-emitting quadrupolar donor–π–acceptor–π–donor (D–π–A–π–D) molecule compound has been synthesised featuring benzo-[1,2-c:4,5-c′]dithiophene-4,8-dione as the acceptor. This molecule was prepared for the purpose of elucidating the origins of the very low photoluminescence quantum yield encountered in its thermally activated delayed fluorescent (TADF) red-emitting isomer which used benzo-[1,2-b:4,5-b′]dithiophene-4,8-dione as the acceptor. The molecule was designed to circumvent the energy gap law, by having a wider HOMO–LUMO gap, while retaining a comparable singlet–triplet gap but ultimately demonstrates even weaker photoluminescence than the red isomer. It shows extremely fast intersystem crossing followed by rapid non-radiative decay and no observable TADF. The electronic structure of this new molecule has been studied using cyclic voltammatery alongside steady-state and transient optical spectroscopy, with observations underpinned by computational insights. To identify whether the observations made from the experimental results might be general properties of benzodithiophene-4,8-dione containing emitters, a computational study is extended to the four isomers of benzodithiophene-4,8-dione in comparison with 9,10-anthraquinone. The results suggest that the singlet and triplet manifolds of these systems are strongly coupled via spin–orbit interactions, and explain how the relative electron-accepting strength of these quinones arises from an interplay between the resonance gains or losses of the central benzene and fused thiophene rings upon photoexcitation. This provides valuable insights into the design principles required for efficient organic light-emitting materials.© The Author(s) , CC BY 3.0论文《阐明以苯并二噻吩-4,8-二酮（benzodithiophene-4,8-dione）为受体的分子内电荷转移化合物的非辐射损耗》的补充材料 本研究合成了一种以苯并[1,2-c:4,5-c']二噻吩-4,8-二酮为受体的新型黄色发射四极给体-π-受体-π-给体（D–π–A–π–D）分子化合物。该分子的设计初衷为阐明以苯并[1,2-b:4,5-b']二噻吩-4,8-二酮为受体的热激活延迟荧光（Thermally Activated Delayed Fluorescence, TADF）红色发射异构体极低光致发光量子产率的起源。 该分子通过更宽的最高占据分子轨道-最低未占据分子轨道能隙（HOMO–LUMO gap）规避能隙定律，同时保持相近的单重态-三重态能隙，但最终其光致发光强度甚至低于该红色异构体。该分子展现出极快的系间窜越过程，随后伴随快速非辐射衰变，且未观测到热激活延迟荧光现象。 研究人员通过循环伏安法（cyclic voltammetry）结合稳态与瞬态光学光谱技术，并辅以计算模拟分析，对该新型分子的电子结构开展了研究。为验证实验观测结果是否为含苯并二噻吩-4,8-二酮发射体的通用性质，本研究将计算分析拓展至苯并二噻吩-4,8-二酮的四种异构体，并与9,10-蒽醌（9,10-anthraquinone）进行对比。 结果表明，此类体系的单重态与三重态电子多重态可通过自旋轨道相互作用实现强耦合，并阐释了这些醌类化合物的相对电子接受能力的起源：其源于光激发下中心苯环与稠合噻吩环的共振增益与损耗之间的相互作用。本研究为高效有机发光材料的设计原则提供了重要参考。 © 作者(s)，CC BY 3.0 许可协议