导电聚合物中极化子动力学的外加电场效应

基于紧束缚近似的Su-Schrieffer-Heeger(SSH)模型,考虑了外电场和Brazovskii-Kirova对称破缺对Hamiltonian的修正,采用非绝热动力学方法研究了一维导电聚合物中正负极化子对的碰撞过程.研究发现外加电场对正负极化子对碰撞的影响至关重要.当外电场很小(约E0<0.02mV/),碰撞的产物是束缚的正负极化子对;在稍强些的电场下,正负极化子可以复合成中性激子,其产率可以达到85%以上;在强电场(约E0>0.2mV/)下则散射成极化子激发态.其中激子形成的细节研究对于如何提高有机电致发光器件的发光效率具有一定的指导意义.

Dynamics Study of Oppositely Charged Polarons under External Electric Fields in Polymers Chain

Within a Su-Schrieffer-Heeger model modified to include an external electric field, the dynamical process of oppositely charged polarons in a polymer chain is simulated by using a nonadiabatic evolution method. It is found that the external electric field plays an important role in the scattering process between o polarons. At external electric fields weaker than a critical one （about E 0 = 0.02 mV/A）, the oppositely charged polaron pair can keep a distance steady to form a bounded-pair. At a slightly larger field, these two oppositely charged polarons can recombine to form a neutral exciton, and the yield of the exciton can reach as high as 85%. Once the field exceeds about E0=0. 2 mV/A, oppositely charged polarons will scatter into a mixed state including polaron-exciton state. The theoretical results may provide useful predictions for improving the electroluminescent efficiency of organic light emitting diodes.