Activated Singlet Exciton Fission in a Semiconducting Polymer
Activated Singlet Exciton Fission in a Semiconducting Polymer
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DOI：
10.1021/ja405427j
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发表时间：
2013-08-28
影响因子：
15
通讯作者：
Clark, Jenny
中科院分区：
文献类型：
--
作者：
Musser, Andrew J.;Al-Hashimi, Mohammed;Clark, Jenny
单重态激子裂变是自旋允许的过程，从单个吸收的光子产生两个三重态激子。这一现象在有机光致变色领域具有巨大的潜力，但其机理仍不清楚。迄今为止，大多数报告都涉及小分子晶体内的分子间裂变。然而，通过适当的化学设计，也可以产生能够分子内分裂的发色团。在这里，我们直接观察到亚100 Is激活的半导体聚（噻吩亚乙烯基）的单线态裂变。我们证明了裂变直接从初始的1B（u）激子，与目前的模型，涉及较低的2A（g）激子。在溶液中，产生的三重态对迅速重组并通过2A（g）态衰变。在薄膜中，激子扩散打破了这种对称性，我们观察到长寿命的三重态，形成电荷转移状态的光伏共混物。
Singlet exciton fission is a spin-allowed process to generate two triplet excitons from a single absorbed photon. This phenomenon offers great potential in organic photo-voltaics, but the mechanism remains poorly understood. Most reports to date have addressed intermolecular fission within small-molecular crystals. However, through appropriate chemical design chromophores capable of intramolecular fission can also be produced. Here we directly observe sub-100 Is activated singlet fission in a semiconducting poly-(thienylenevinylene). We demonstrate that fission proceeds directly from the initial 1B(u) exciton, contrary to current models that involve the lower-lying 2A(g) exciton. In solution, the generated triplet pairs rapidly recombine and decay through the 2A(g) state. In films, exciton diffusion breaks this symmetry and we observe long-lived triplets which form charge-transfer states in photovoltaic blends.