INTRA-MOLECULAR CARRIER CONDUCTION OF CONDUCTING POLYMERS

点击翻译按钮获取中文摘要

In the solid of conducting polymers, there exist three kinds of carrier transport mechanisms, i.e., the intramolecular, intermolecular and interfibrillar ones. Then, it is difficult to distinguish each contribution by a conventional, macroscopic measurement' of the conductivity. On the other hand, when conjugated conducting polymers are dissolved in an organic solvent, we can selectively obtain the information on the one-dimensional intra-molecular conduction, because the polymer chains are isolated from each other in the solvent as an insulator. Hence, we have applied the dynamic electric birefringence spectroscopy to the solution of conducting polymers in order to reveal the relation between mainchain conformation of polymers and intra-molecular carrier transports.In this study, we have developed an apparatus for measuring the dynamic electric birefringence in a wide frequency range, than applied it to the solution of a typical soluble conducting polymer, poly(3-hexlythophene)(P3HT). As a results, it was found that the intramolecular conduction of P3HT in pure dichloromethane showed two kinds of transport processes of polarons with different diffusion distances and diffusion constants. The slower relaxation was ascribed to the diffusion within the longer distance up to the contour length. The faster relaxation was attributed to come from the diffusion within a more local range. The existence of two carrier transport processes reflects a strong disorder effect in the one-dimensional system of conducting polymers.Further, we have applied this method to the solution of polyaniline (PAni), and revealed the relationship between the mainchain conformation and the intra-molecular conduction.In this study, we indicated that the dynamic electric birefringence spectroscopy is a useful technique for investigation of the main-chain conformation and the intrachain conduction mechanisms of conducting polymers.