Wang Qian, Gao Yuan-Jun, Zhang Ting-Ting, Han Juan, Cui Ganglong
Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University Beijing 100875 P. R. China
Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University Linfen 041000 P. R. China.
RSC Adv. 2019 Jul 3;9(36):20786-20795. doi: 10.1039/c9ra02256b. eCollection 2019 Jul 1.
The QM/MM method is employed to investigate the photophysical mechanism of two dinuclear copper iodide complexes with thermally activated delayed fluorescence (TADF). The S-T energy differences (Δ ) in these two complexes are small enough so that repopulating the S state from T becomes energetically allowed. Both forward and reverse intersystem crossing (ISC and rISC) processes are much faster than the corresponding radiative fluorescence and phosphorescence processes [ (10 s) > (10 s), (10 s) > (10 s)]. The faster rISC process than the phosphorescence emission enables TADF. Moreover, the diphosphine ligands are found to play an important role in regulating the electronic structures and thereto the radiative and nonradiative rate constants. The present work rationalizes experimental phenomena and helps understand the intrinsic luminescence properties. The obtained insights could be useful for tuning the luminescence performance of dicopper-based luminescence materials.
采用量子力学/分子力学（QM/MM）方法研究了两种具有热活化延迟荧光（TADF）的双核碘化铜配合物的光物理机制。这两种配合物中的单重态-三重态能量差（Δ）足够小，以至于从三重态重新填充到单重态在能量上是允许的。正向和反向系间窜越（ISC和rISC）过程都比相应的辐射荧光和磷光过程快得多[（10⁻⁶ s）> （10⁻⁹ s），（10⁻⁶ s）> （10⁻¹² s）]。比磷光发射更快的rISC过程实现了TADF。此外，发现二膦配体在调节电子结构以及辐射和非辐射速率常数方面起着重要作用。本工作解释了实验现象，并有助于理解其内在发光特性。所获得的见解可能有助于调节基于二铜的发光材料的发光性能。
