链间耦合对聚合物分子中激子形成的影响

从紧束缚模型出发，研究了聚合物分子中链间耦合对激子形成的影响.结果表明:光激发后耦合分子体系中形成的激子态有两种可能的分布:一种是激子在强耦合下仍主要局域在一条链中（称为链间定域激子）；另一种是激子在链间平均扩展（称为链间扩展激子）.通过计算链间耦合强度对这2种激子态的产生能和束缚能的影响，发现耦合体系中激发的电子－空穴更容易复合形成链间定域激子.另外，通过分析链间耦合强度对激子束缚能的影响，表明聚合物分子之间的耦合不利于激子形成，因此固态薄膜的光致发光效率要低于其溶液状态.

EXCITON FORMATION WITH INTERCHAIN COUPLINGS IN ORGANIC POLYMERS

Based on the framework of the tight binding approach, the formation of an exciton in inter-coupled polymer chains is studied. Both a localized exciton in one single chain and a spread exciton between chains are obtained. It is found that an excited electron-hole pair is more inclined to evolve into a localized exciton. By analyzing the effect of the interchain couplings on the exciton binding energy, it is shown that the photoluminescence efficiency of the polymer in a dilute solution state is higher than that in a solid state.