Research On The Carrier Transportation Dynamics In The Conducting Polymers

In recent years, researches on polymers have made rapid progress, especially in the study of conducting polymers. Several factors have greatly affected this rapid progress. On the one hand, conductive polymers not only show metallic properties but also are known for their low cost in resource. On the other hand, nonlinear excitations, such as solitons and polarons, are found to be the major charge carriers in conductive polymers. Up to now, many optical electronic devices are designed fundamentally by conductive polymers, for example light emitting diodes, field effect transistors, and so on.In organic-based light emitting devices, as electrons or holes are injected into the organic layers from electrodes, polarons will form due to the interaction between electrons and phonons. If electric fields are applied along the polymer, the formed polaron will move along the polymer in the direction of the electric field and jump to the electrode. This essay will mainly discuss polaron dynamic processes in the presence of external electric fields.In the first chapter, we discuss the basic structure of polymer and Peierls phase transition theory.In the second chapter, we introduce a classical model——SSH model. At the same time, we introduce a non-adiabatic dynamic method.In the third chapter, we focus on dynamic processes of polarons within the non- adiabatic method. In the polymer/metal structure, we mainly discuss the following two processes, polaronic motion along the polymer chain and charge tunneling into the metal electrode. The numerical simulation results show that, (1) if the electronic field is weak, the polaron can not jump to the metal until the coupling coefficient between the polymer and the electrode is increased. Discussions are also carried out on polaronic velocity with respect to electric field strength; (2) the electric field is strong, the field will drive the polaron to the polymer end, and jump to the metal electrode. At the same time, we also analyze the effect of electrode Fermi level on charge transportation from polymers to electrodes.In the fourth chapter, summaries are given.