共轭聚合物中受激吸收与受激辐射的量子动力学研究  

Dynamical study on the stimulated absorption and emission in a conjugated polymer

作　　者：王文静[1] 孟瑞璇 李元[3] 高琨[2,3] 

机构地区：[1]齐鲁师范学院物理与电子工程学院,济南250013 [2]山东大学物理学院,晶体材料国家重点实验室,济南250100 [3]佐治亚理工学院,化学与生物化学系,亚特兰大30332

出　　处：《物理学报》2014年第19期331-342,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:21161160445);国家留学基金委公派访问学者项目;山东省自然科学基金(批准号:ZR2013AM019);山东大学自主创新基金(批准号:2012ZD034)资助的课题~~

摘　　要：基于扩展的一维SSH紧束缚模型结合非绝热的分子动力学方法,理论研究了共轭聚合物分子(PPV)在光脉冲作用下受激吸收和受激辐射的量子动力学过程.首先,设定分子初始处于基态,讨论了受激吸收过程中不同的电子受激跃迁模式与光激发脉冲的关系.通过对终态的分析,发现分子受激后只能产生电子-空穴的束缚态,包括:激子、双激子和高能激子.计算了各种激发态的产率,特别是,给出了各种激发态产率与光激发能量的定量关系.此外,基于实验,分别讨论了光激发强度对高能激子和双激子产率的影响,并与实验结果进行了比较.最后,设定分子初始分别处于激子和双激子态,研究了分子内定域能级之间的受激辐射过程,并简单讨论了激子和双激子受激辐射与光激发能量及强度的关系.By applying a femtosecond electric pump pulse to a poly（p-phenylene vinylene）（PPV） molecule, we theoretically investigate the dynamical processes for its stimulated absorption and emission. The simulations are performed within the framework of an extended version of one-dimensional Su–Schrieffer–Heeger tight-binding model combined with a nonadiabatic evolution method. Firstly, we set the molecule initially lying in the ground state, by which we give the relation between different stimulated transition modes and the photoexciting pulse. Analysis of the final states shows that we can only obtain some electron-hole binding states by an external optical excitation for the molecule, which includes exciton, biexciton, and high-energy exciton. We have calculated their yields and find that they are determined by the optical excitation energy. In addition, based on the experimental observations, we separately investigate the effect of the optical excitation intensity on the yields of biexciton and high-energy exciton. The calculated results are consistent with the corresponding experimental speculations. Finally, by setting the molecule lying in an exciton or a biexciton, we focus on the stimulated emission process between their generated intragap states. Effects of the optical excitation energy and intensity on them are separately analyzed. These results might be of great importance for further improving the optical applications of polymers, especially for optimizing the polymer photovoltaic and laser properties.

关 键 词：聚合物 受激吸收 受激辐射 激子 

分 类 号：O413.1[理学—理论物理]