Revealing the Contest between Triplet-Triplet Exchange and Triplet-Triplet Energy Transfer Coupling in Correlated Triplet Pair States in Singlet Fission.
Revealing the Contest between Triplet-Triplet Exchange and Triplet-Triplet Energy Transfer Coupling in Correlated Triplet Pair States in Singlet Fission.
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DOI：
10.33774/chemrxiv-2021-5lhjx-v2
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
Vibin Abraham;N. Mayhall
中科院分区：
文献类型：
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作者：
Vibin Abraham;N. Mayhall
理解相关三重态对1（TT）中间体的分离对于利用单线态裂变来提高太阳能电池效率至关重要。这种分离机制由两个关键相互作用主导：（i）三重态之间的交换相互作用（K），其导致双激子态自旋分裂为1（TT），3（TT）和5（TT）态，以及（ii）三重态-三重态能量转移积分（t），其使得能够形成空间分离（但仍然是自旋纠缠）态1（T···T）。我们开发了一个简单的从头计算技术来计算双激子交换（K）和双激子转移耦合。我们的关键发现揭示了成功的相关三重态对解离的新条件。双激子交换相互作用需要是铁磁性的或对于三重态能量转移可以忽略不计，以实现有利的解离。我们还探讨了生色团包装的效果，以揭示几何形状，这些条件是实现并四苯。
Understanding the separation of the correlated triplet pair state 1(TT) intermediate is critical for leveraging singlet fission to improve solar cell efficiency. This separation mechanism is dominated by two key interactions: (i) the exchange interaction (K) between the triplets which leads to the spin splitting of the biexciton state into 1(TT),3(TT) and 5(TT) states, and (ii) the triplet-triplet energy transfer integral (t) which enables the formation of the spatially separated (but still spin entangled) state 1(T···T). We develop a simple ab initio technique to compute both the biexciton exchange (K) and biexciton transfer coupling. Our key findings reveal new conditions for successful correlated triplet pair state dissociation. The biexciton exchange interaction needs to be ferromagnetic or negligible to the triplet energy transfer for favorable dissociation. We also explore the effect of chromophore packing to reveal geometries where these conditions are achieved for tetracene.