Dynamics and mechanism of delocalized cationic state in organic photoconductive polymers

为了阐明光诱导分子组件中电荷分离在电荷分离状态下发生快速电荷转移反应的因素，我们研究了固相芳基乙烯聚合物体系中芳基之间在光激发后发生快速电荷转移反应的电子转移动力学。在10 ~ 295 K的温度范围内，通过飞秒瞬态吸收光谱和二色性测量表明，阳离子态的离域过程在几个芳香基团之间发生得非常迅速。这种离域导致阴离子和阳离子之间离子间距离的增加，从而导致吸引库仑相互作用的减少，阳离子尺寸的增加降低了重组能。这些因素促进了传统电子转移理论不能很好地解释的快速电荷转移反应。

To elucidate factors enabling the rapid charge shift reaction in the charge-separated state produced by photoinduced charge separation in molecular assemblies, we have studied the electron transfer dynamics in aromatic vinyl polymer systems in solid phase where rapid charge shift reaction takes place among aromatic groups after the photoexcitation. By femtosecond transient absorption spectroscopy and dichroism measurements in the temperature range of 10 to 295 K, it was revealed that the delocalization process of the cationic state occurred among several aromatic groups very rapidly. This delocalization leads to the increase in the inter-ionic distance between the anion and the cation resulting in the reduction of the attractive Coulombic interaction and the increase in the cationic size reduces the reorganization energy. These factors facilitate the rapid charge shift reaction which has not been well accounted for by the conventional electron transfer theories.