电场作用下聚对苯亚胺中的激子行为

Behavior of Exciton in a Pernigraniline-base under Electric Field

从扩展的Ginder Epstein(GE)模型出发,计入静电场,数值模拟了有限长开链聚对苯亚胺(pernigrani line base)中的激子态。计算表明,当场强为零时,激子是自陷(self trapped)束缚的极化子激子;随着电场强度的增加,缺陷将沿电场方向发生移动(无论正反向施以电场);而当E≥3 6×104V/cm时,激子被静电场解离,形成正、负极化子而束缚在链端。本文关于零电场和强电场时的激子行为与李蕾,傅柔励等人关于m LPPP等电致发光材料的结果十分相似,但在弱电场时,并未出现预料中的极化,疑与本文引用的模型有关。

The discovery of electroluminescence in polymers has greatly promoted the development of LED. Exciton play an important role in those materials. Polyaniline, which belongs to the family of conducting polymers, has been the focus of increased physical and chemical studies in the past several years. It has been demonstrated that polyaniline may be distinguished in three discrete oxidation states, namely, leucoemeraldinebase (LB), emeraldinebase (EB) and pernigranilinebase (PNB). The research works about exciton of the pernigranilinebase (PNB), the fully oxidation of polyaniline, are less reported, a possible reason is that the chemical and electronic structure of this polymer are very complicated. In this paper, exciton in a PNB polymer under the electric field has been studied in the framework of the extended GinderEpstein model. In the earlier works, Liu Jie et al. has succeeded in explaining some experimental data of the PNB polymer by using this model and brought forth some new concepts such as combined polarons and combined solitons. Our numerical simulations showed that the exciton in this polymer is selftrapped and it consists of a bond order exciton associated with a ring torsion exciton. Further calculations showed that it will move along the main chain in weak electric field. When E≥36×104V/cm, the exciton is dissociated into a pair of positive and negative polarons. Polarization of the exciton has not been found in our work. We suggest that the model be modified such as the electronic interference be considered. The results about the behavior of exciton in zero and strong electric field are very similar to those of the conducting polymers such as mLPPP, which has ever been calculated by Li Lei et al. We still have not found the relevant experimental data, so the above numerical solutions can only be considered as a reference.