共轭高分子中激子形成的非绝热动力学研究

有机共轭高分子被光激发后,其电子结构会发生明显的变化,通过非绝热数值计算的方法模拟了受光激发后有机高分子中激子生成的动力学过程.结果表明,激子的生成一般需要数十飞秒时间,激子的生成周期随分子链长度的增大而增大.高激发态激子可以根据生成周期分为两类,第一类激子的生成周期在数十到上百飞秒之间,第二类激子的生成周期可达上千飞秒.对于超过200个碳原子的高分子,第二类激子的生成周期可达5000飞秒以上.这个计算结果说明,相比于有机高分子,有机小分子中更容易观测到激子.

Nonadiabatic dynamics study upon exciton formation in a conjugated polymer chain

After photo-excitation, the electronic structure of organic conjugated polymers will change greatly. A nonadiabatic numerical method is used to study the dynamical process of exciton formation in photo-excited polymers. It shows that exciton formation generally covers several tens of femtoseconds. In addition, the creation period increases with the increasing length of the polymer chain. Highly excited excitons can be classified into two types according to creation period. For one type, the creation period varies from several tens of femtoseconds to more than one hundred femtoseconds. For the other, the creation period can be over one thousand femtoseconds. For the polymers including more than 200 monomers, the creation period can exceed 5000 femtoseconds. This result indicates that excitons can be more readily found in oligomers than in polymers.