Singlet fission and triplet–triplet annihilation represent two highly promising ways of increasing the efficiency of photovoltaic devices. Both processes are believed to be mediated by a biexcitonic triplet-pair state, ¹(TT). Recently however, there has been debate over the role of ¹(TT) in triplet–triplet annihilation. Here we use intensity-dependent, low-temperature photoluminescence measurements, combined with kinetic modelling, to show that distinct ¹(TT) emission arises directly from triplet–triplet annihilation in high-quality pentacene single crystals and anthradithiophene (diF-TES-ADT) thin films. This work demonstrates that a real, emissive triplet-pair state acts as an intermediate in both singlet fission and triplet–triplet annihilation and that this is true for both endo- and exothermic singlet fission materials.

单线态裂变和三线态-三线态湮灭代表了两种非常有前途的提高光伏器件效率的方法。这两个过程都被认为是由双激子三重对状态¹ (TT)介导的。然而，最近关于¹ (TT) 在三重态-三重态湮灭中的作用一直存在争议。在这里，我们使用强度相关的低温光致发光测量，结合动力学建模，来表明不同的¹(TT) 发射直接来自高质量并五苯单晶和蒽二噻吩 (diF-TES-ADT) 薄膜中的三重态-三重态湮灭。这项工作表明，真实的、发射的三线态对状态在单线态裂变和三线态-三线态湮灭中都充当中间体，这对于吸热和放热单线态裂变材料都是如此。