次近邻电子跳跃对PNB聚合物中极化子能级与晶格位形的影响

Effects of next-nearest-neighbor hopping on the energy spectrum and the configuration of the polarons in pernigraniline-base polymer

在Baranowski-Buttner-Voit(BBV)模型的基础上,讨论了次近邻电子跳跃对PNB(pernigraniline—base)聚合物中空穴型极化子和电子型极化子能谱结构及晶格位形的影响,数值计算表明:(1)逐渐增强的次近邻作用可使两类极化子导带宽度变小,价带宽度变大,极化子能级之间的跃迁能逐渐减小;电子型极化子的宽度明显变小,而空穴型极化子几乎不变;(2)通过与Leng J M等人的实验结果对比,确定极化子晶格中的次近邻跳跃强度β<0.08。

In this paper we investigate the effects of next-nearest-neighbor hopping on the electronic structure and the lattice configuration of the positive and negative polarons on the basis of Baranowski- Buttner-Voit model. For the two kinds of polarons, it is found that the increase of the next-nearestneighbor coupling strength leads to the valence band（VB） expands to a larger range while the conduction band（CB） acts to the contrary, as well as the transition energy from the lower gap state to the higher one decreases gradually. Our numerical results also shows that the width of the negative polarons decreases obviously while that of the positive polarons varies slightly. We suggest the next-nearest-neighbor coupling strength take β〈 0.08 by comparing with the experimental data of Leng J M et al.