Wang Zhiwei, Liu Heyuan, Xie Xiaoyu, Zhang Chunfeng, Wang Rui, Chen Lan, Xu Yihe, Ma Haibo, Fang Weihai, Yao Yao, Sang Hai, Wang Xiaoyong, Li Xiyou, Xiao Min
National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
School of Materials Science and Engineering, Institute of New Energy, China University of Petroleum (East China), Qingdao, China.
Nat Chem. 2021 Jun;13(6):559-567. doi: 10.1038/s41557-021-00665-7. Epub 2021 Apr 8.
Singlet fission (SF) can potentially boost the efficiency of solar energy conversion by converting a singlet exciton (S) into two free triplets (T + T) through an intermediate state of a correlated triplet pair (TT). Although efficient TT generation has been recently realized in many intramolecular SF materials, their potential applications have been hindered by the poor efficiency of TT dissociation. Here we demonstrate that this can be overcome by employing a spatially separated (T…T) state with weak intertriplet coupling in tetracene oligomers with three or more chromophores. By using transient magneto-optical spectroscopic methods, we show that free-triplet generation can be markedly enhanced through the SF pathway that involves the spatially separated (T…T) state rather than the pathway mediated by the spatially adjacent TT state, leading to a marked improvement in free-triplet generation with an efficiency increase from 21% for the dimer to 85% (124%) for the trimer (tetramer).
单重态裂变（SF）有可能通过将单重态激子（S）通过相关三重态对（TT）的中间态转化为两个自由三重态（T + T）来提高太阳能转换效率。尽管最近在许多分子内SF材料中已经实现了高效的TT生成，但其潜在应用却因TT解离效率低下而受到阻碍。在这里，我们证明，通过在具有三个或更多发色团的并四苯低聚物中采用具有弱三重态间耦合的空间分离（T…T）态，可以克服这一问题。通过使用瞬态磁光光谱方法，我们表明，通过涉及空间分离（T…T）态的SF途径而不是由空间相邻的TT态介导的途径，可以显著增强自由三重态的生成，从而导致自由三重态生成的显著改善，效率从二聚体的21%提高到三聚体（四聚体）的85%（124%）。
