中文摘要：

化学计算证实了光致激发窄带系聚合物APFO3后，会发生链内电荷转移（ICT）过程，同时这一特性还影响了吸收光谱中的第一吸收带. 瞬态吸收结果再一次表明了当聚合物在单分散体系中确实存在ICT特性，而且这种特性会同振动弛豫竞争. 在聚集态中，受链间相互作用的影响，ICT特性会消失，而且激子弛豫过程将在光致激发后的弛豫过程中占据主导地位. 混有PC61BM的APFO3薄膜的光致激发动力学显示，当PC61BM 的含量超过50%时，激子解离已经达到饱和. 基于此异质节的光伏器件性能显示PC61BM的含量高于50％以后，光电流的增幅也很小．

英文摘要：

The excited state photophysics of low bandgap polymer APFO3 has been investigated in detail. The chemical calculations confirm that the intrachain charge transfer （ICT） may occur after photo-excitation and is mainly responsible for the first absorption band. The transient absorption results confirm that ICT indeed exists and competes with the vibra-tional relaxation at the same time, when APFO3 is in a monodisperse system. This ICT process would disappear due to the influence of interchain interaction when APFO3 is in the condensed phase, where the exciton decay would be dominant in the relaxation process after photoexcitation. The photoexcitation dynamics of APFO3 film blending with PC61BM are presented, which shows that the exciton may be dissociated completely as the percentage of PC61BM reaches ～50%. Meanwhile, the photovoltaic performance based on blend het-erojunction shows that the increase of photocurrent is little if the percentage of PC61BM exceeds ～50%. Overall, the present study has covered several fundamental processes taking place in the APFO3 polymer.