State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing, China, 100871.
J Phys Chem B. 2010 Mar 4;114(8):2602-6. doi: 10.1021/jp909271e.
We report herein the photophysics of three two-dimensional polythiophene derivatives, with different lengths of thienylene-vinylene conjugated side chains, in comparison with regioregular poly(3-hexylthiophene) (P3HT). In solution, an evolution from stimulated emission to photoinduced absorption (PIA) at emission peak is discovered with increasing length of side chains, indicating larger steric hindrance by longer side chains. The exciton lifetime is reduced by a factor of five when the thienylene-vinylene side chain is prolonged to three units. In the film form, we investigate the dynamics of the two PIA bands, assigned to intrachain exciton and interchain polaron pairs, respectively. The analysis of the dynamics suggests that their intrachain exciton decays are similar to the one-dimensional P3HT. The recombination possibility of delocalized interchain polaron pairs occurring in 0.9 ps is reduced with longer thienylene-vinylene side chain samples. Compared with regioregular P3HT film, which self-organizes to form lamellae crystal morphology, the morphologies of these three two-dimensional polythiophenes are amorphous, attributed to the large steric hindrance caused by the existence of side chains. This design of polythiophene derivatives provides the reduction of recombination possibility for delocalized interchain polaron pairs generated in the polymer.
我们在此报告三种二维聚噻吩衍生物的光物理性质，这些衍生物具有不同长度的噻吩-亚乙烯基共轭侧链，与区域规整的聚（3-己基噻吩）（P3HT）进行了比较。在溶液中，随着侧链长度的增加，从受激辐射到发射峰处的光致吸收（PIA）的演化被发现，这表明较长的侧链具有更大的空间位阻。当噻吩-亚乙烯基侧链延长至三个单元时，激子寿命缩短了五倍。在薄膜形式中，我们研究了两个 PIA 带的动力学，分别分配给链内激子和链间极化子对。动力学分析表明，它们的链内激子衰减类似于一维 P3HT。具有较长噻吩-亚乙烯基侧链样品的离域链间极化子对的复合可能性在 0.9 ps 内降低。与自组装形成层状晶体形态的区域规整 P3HT 薄膜相比，这三种二维聚噻吩的形态为无定形，这归因于侧链存在引起的大空间位阻。这些聚噻吩衍生物的设计提供了减少聚合物中生成的离域链间极化子对复合的可能性。
