INTRA-MOLECULAR CARRIER CONDUCTION OF CONDUCTING POLYMERS

在导电聚合物固体中，存在分子内、分子间和纤维间三种载流子传输机制。然后，很难通过传导性的常规宏观测量来区分每种贡献。另一方面，当共轭导电聚合物溶解在有机溶剂中时，我们可以选择性地获得一维分子内导电的信息，因为聚合物链在溶剂中是相互隔离的，作为绝缘体。因此，我们将动态双折射光谱应用到导电聚合物的溶液中，以揭示聚合物的主链构象与分子内载流子输运之间的关系。在本研究中，我们研制了一种在较宽频率范围内测量动态双折射的装置，并将其应用于典型的可溶性导电聚合物聚(3-己基苯基)(P3HT)的溶液。结果发现，P3HT在纯二氯甲烷中的分子内传导表现为两种不同扩散距离和扩散常数的极化子输运过程。较慢的松弛归因于距离较长至等高线长度的扩散。更快的松弛被归因于来自更局部范围内的扩散。两个载流子输运过程的存在反映了导电聚合物一维体系中强烈的无序效应。此外，我们将这种方法应用于聚苯胺(PANI)的溶液，揭示了主链构象与分子内电导之间的关系。在本研究中，动态电双折射光谱是研究导电聚合物主链构象和链内导电机理的一种有用的技术。

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.