Theoretical Investigation of Singlet Fission in Molecular Dimers: The Role of Charge Transfer States and Quantum Interference
Theoretical Investigation of Singlet Fission in Molecular Dimers: The Role of Charge Transfer States and Quantum Interference
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DOI：
10.1021/jp503398a
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发表时间：
2014-07-03
影响因子：
3.7
通讯作者：
Grozema, Ferdinand C.
中科院分区：
文献类型：
--
作者：
Mirjani, Fatemeh;Renaud, Nicolas;Grozema, Ferdinand C.
单线态裂变（SF）是一种允许自旋的过程，由单线态激发态分裂成一对三重态。这个过程可以潜在地将有机太阳能电池的效率提高1.5倍。在本文中，我们研究了SF在PDI衍生物、并戊烯和1,3-二苯基异苯并呋喃（DPB）的不同分子聚集体中的动力学。为了计算SF速率，我们采用了马尔可夫密度矩阵传播方法来模拟分子二聚体中的SF。这种方法允许对协调三元组形成的相干和非相干过程进行解释。我们的计算表明，SF在PDI衍生物中的反应速度比在并五苯和DPB中的反应速度快得多。我们的分析还表明，SF主要是由一种超交换机制介导的，该机制涉及电荷转移态作为虚拟中间体。此外，由于三重态形成的不同途径的存在，量子干涉的特征被清晰地观察到。
Singlet fission (SF) is a spin-allowed process by which a singlet excited state splits into a pair of triplet states. This process can potentially increase the efficiency of organic solar cells by a factor of 1.5. In this article, we study the dynamics of SF in different molecular aggregates of perylenediimide (PDI) derivatives, pentacene, and 1,3-diphenylisobenzofuran (DPB). To compute the SF rate, we have adopted a Markovian density matrix propagation approach to model SF in a molecular dimer. This approach allows accounting for both the coherent and incoherent processes that mediate the triplet formation. Our calculations show that SF can be much faster in PDI derivatives than in pentacene and DPB. Our analysis also indicates that SF is principally mediated by a superexchange mechanism that involves charge transfer states as virtual intermediates. In addition, because of the existence of different pathways for the formation of the triplet states, signatures of quantum interference are clearly observed.