澳大利亚悉尼大学Schmidt, Timothy W.团队报道了磁场揭示了单线态裂变中三重对多激子光致发光的特征。相关研究成果发表在2024年7月25日出版的国际学术期刊《自然—化学》。

单线态裂变和三重态聚变的光物理过程有许多新兴的应用。它们分别涉及将光生单线态激子分离为两个暗三重态激子，以及将两个暗三重态激子融合为发射单线态激子。准分子态在这些过程中的作用和三重态对态的性质一直存在争议。

该文中，研究人员分析了纯液体单线态裂变发色团的室温时间分辨发射，并表明它具有三个光谱分量：两个对应于亮单线态和准分子态，第三个分量在三重态聚变过程中变得更加突出。磁场增强了这一光谱，证实了其起源于弱耦合三重态对的复合。因此，它被归因于强耦合的三重态对。这些观察结果统一了这样一种观点，即单线态裂变和三重态聚变中存在一种发射中间体，与广泛的、非结构化的准分子发射不同。

附：英文原文

Title: Magnetic fields reveal signatures of triplet-pair multi-exciton photoluminescence in singlet fission

Author: Feng, Jiale, Hosseinabadi, Parisa, de Clercq, Damon M., Carwithen, Ben P., Nielsen, Michael P., Brett, Matthew W., Prasad, Shyamal K. K., Farahani, Adam A. D., Li, Hsiu L., Sanders, Samuel N., Beves, Jonathon E., Ekins-Daukes, N. J., Cole, Jared H., Thordarson, Pall, Huang, David M., Tayebjee, Murad J. Y., Schmidt, Timothy W.

Issue&Volume: 2024-07-25

Abstract: The photophysical processes of singlet fission and triplet fusion have numerous emerging applications. They involve the separation of a photo-generated singlet exciton into two dark triplet excitons and the fusion of two dark triplet excitons into an emissive singlet exciton, respectively. The role of the excimer state and the nature of the triplet-pair state in these processes have been a matter of contention. Here we analyse the room temperature time-resolved emission of a neat liquid singlet fission chromophore and show that it exhibits three spectral components: two that correspond to the bright singlet and excimer states and a third component that becomes more prominent during triplet fusion. This spectrum is enhanced by magnetic fields, confirming its origins in the recombination of weakly coupled triplet pairs. It is thus attributed to a strongly coupled triplet pair state. These observations unite the view that there is an emissive intermediate in singlet fission and triplet fusion, distinct from the broad, unstructured excimer emission.

DOI: 10.1038/s41557-024-01591-0

Source: https://www.nature.com/articles/s41557-024-01591-0