南京大学Min Xiao研究团队和中国石油大学Xiyou Li团队合作发现，通过空间分离的三重态对态在四烯低聚物中更高效地产生自由三重态。 这一研究成果于2021年4月8日发表在国际顶尖学术期刊《自然-化学》上。

研究人员表示，单重态裂变(SF)通过一个相关的三重态对(TT)的中间态，将单线激子(S₁)转化为两个自由的三重态(T₁+T₁)，从而有可能提高太阳能转换效率。尽管最近已经在许多分子内SF材料中实现了有效的TT生成，但是由于TT解离效率低而阻碍了它们的潜在应用。

课题组验证了该问题可以在含有三个或更多发色团的四烯低聚物中，通过采用具有弱三重态间偶联的空间分离的¹(T…T)态来克服。通过使用瞬态磁光学光谱方法，研究人员展示了自由三重态的产生可以通过含有空间分离¹(T…T)态的路径而不是空间相邻TT态介导的路径而显著性地增强，导致自由三重态产生效率从对于二聚体的21%显著提高到对于三聚体（四聚体）的85%（124%）。

附：英文原文

Title: Free-triplet generation with improved efficiency in tetracene oligomers through spatially separated triplet pair states

Author: Zhiwei Wang, Heyuan Liu, Xiaoyu Xie, Chunfeng Zhang, Rui Wang, Lan Chen, Yihe Xu, Haibo Ma, Weihai Fang, Yao Yao, Hai Sang, Xiaoyong Wang, Xiyou Li, Min Xiao

Issue&Volume: 2021-04-08

Abstract: Singlet fission (SF) can potentially boost the efficiency of solar energy conversion by converting a singlet exciton (S1) into two free triplets (T1+T1) 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 1(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 1(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).

DOI: 10.1038/s41557-021-00665-7

Source: https://www.nature.com/articles/s41557-021-00665-7