Triplet Transfer Mediates Triplet Pair Separation during Singlet Fission in 6,13-Bis(triisopropylsilylethynyl)-Pentacene
Triplet Transfer Mediates Triplet Pair Separation during Singlet Fission in 6,13-Bis(triisopropylsilylethynyl)-Pentacene
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DOI：
10.1002/adfm.201703929
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发表时间：
2017-12-08
影响因子：
19
通讯作者：
Asbury, John B.
中科院分区：
文献类型：
--
作者：
Grieco, Christopher;Doucette, Grayson S.;Asbury, John B.
6,13-双（三异丙基乙基）并五苯（TIPS-Pn）分离多晶态溶液铸膜的三重态居群动力学提供了定量实验证据，证明三重态激发能转移是单线态裂变过程中相关三重态对（CTP）分离的主要机制。比较了TIPS-Pn多晶的CTP分离速率变化及其由晶体结构控制的三重态扩散特性。由于三重态能量转移是一个自旋禁止的过程，需要直接的波函数重叠，因此使用简单的电子和空穴转移积分计算来预测分子包装排列如何影响三重态转移速率。传递积分揭示了包装排列的差异如何影响TIPS-Pn分子对之间的电子相互作用，这与多晶中CTP分离的相对速率有关。这些发现表明，相对简单的计算与分子填充结构的测量相结合，可以作为筛选工具，先验地预测新型单线态裂变敏化剂是否有可能经历CTP态的快速分离，形成三重态。
Triplet population dynamics of solution cast films of isolated polymorphs of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn) provide quantitative experimental evidence that triplet excitation energy transfer is the dominant mechanism for correlated triplet pair (CTP) separation during singlet fission. Variations in CTP separation rates are compared for polymorphs of TIPS-Pn with their triplet diffusion characteristics that are controlled by their crystal structures. Since triplet energy transfer is a spin-forbidden process requiring direct wavefunction overlap, simple calculations of electron and hole transfer integrals are used to predict how molecular packing arrangements would influence triplet transfer rates. The transfer integrals reveal how differences in the packing arrangements affect electronic interactions between pairs of TIPS-Pn molecules, which are correlated with the relative rates of CTP separation in the polymorphs. These findings suggest that relatively simple computations in conjunction with measurements of molecular packing structures may be used as screening tools to predict a priori whether new types of singlet fission sensitizers have the potential to undergo fast separation of CTP states to form multiplied triplets.