Casanova David
Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU) and Donostia International Physics Center (DIPC) , P.K. 1072, 20080 Donostia, Euskadi, Spain.
IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Euskadi, Spain.
J Chem Theory Comput. 2015 Jun 9;11(6):2642-50. doi: 10.1021/acs.jctc.5b00144.
This paper reintroduces and explores the generation of two bright states from a single photon via a singlet fission mechanism in organic materials. This particular photophysical process is labeled here as bright fission (BF). The central part of the study is devoted to set the theoretical foundations of BF by discussing possible electronic mechanisms, the role of different excited states with various physical nature, the presence of competing deactivation channels, and the possible requirements for the BF viability. In a second part, some of the properties related to BF are computationally explored in anthracene. The analysis of computed high-lying excited states identifies several optical transitions as good candidates to trigger BF in anthracene. The approximation of excitonic couplings of these high energy levels to other electronic states within the same energy range suggests possible paths to populate electronic configurations potentially able to split in two independent spin singlets, i.e. singlet-singlet states. The study also explores the electronic structure of the energetically lowest singlet-singlet states in anthracene dimers and discusses the presence of charge transfer configurations and their relation to the singlet-singlet manifold. The computational results suggest fast relaxation to the lowest singlet-singlet state, from which the excitonic fission may occur. All in all, the present work aims at motivating to pursue further efforts in the study of the BF process in organic materials.
本文重新介绍并探讨了通过有机材料中的单重态裂变机制从单个光子产生两个亮态的过程。这种特殊的光物理过程在此处被标记为亮裂变（BF）。研究的核心部分致力于通过讨论可能的电子机制、具有各种物理性质的不同激发态的作用、竞争失活通道的存在以及BF可行性的可能要求来奠定BF的理论基础。在第二部分中，在蒽中通过计算探索了与BF相关的一些性质。对计算得到的高能激发态的分析确定了几个光学跃迁是引发蒽中BF的良好候选者。将这些高能级的激子耦合近似到相同能量范围内的其他电子态，表明了可能的途径来填充潜在能够分裂为两个独立自旋单重态的电子构型，即单重态 - 单重态态。该研究还探索了蒽二聚体中能量最低的单重态 - 单重态态的电子结构，并讨论了电荷转移构型的存在及其与单重态 - 单重态流形的关系。计算结果表明快速弛豫到最低的单重态 - 单重态态，激子裂变可能由此发生。总而言之，目前的工作旨在推动在有机材料中BF过程的研究方面做出进一步努力。
