INTRA-MOLECULAR CARRIER CONDUCTION OF CONDUCTING POLYMERS

在导电聚合物固体中，载流子的传递机制主要有分子内、分子间和纤维间三种。然后，很难通过传统的宏观电导率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，由于聚合物链在溶剂中作为绝缘体相互隔离，我们可以选择性地获得一维分子内导电的信息。因此，我们将动态电双折射光谱应用于导电聚合物溶液中，以揭示聚合物主链构象与分子内载流子传输之间的关系。在这项研究中，我们开发了一种测量宽频率范围内动态电双折射的装置，并将其应用于典型的可溶性导电聚合物聚（3-己基噻吩）（P3HT）的溶液中。结果发现，P3HT在纯二氯甲烷中的分子内传导表现出两种极化子的传递过程，且具有不同的扩散距离和扩散常数。较慢的弛豫是由于在较长的距离内扩散到轮廓长度。更快的弛豫归因于在更局部范围内的扩散。两个载流子输运过程的存在反映了一维导电聚合物体系中强烈的无序效应。此外，我们还将该方法应用于聚苯胺（PAni）溶液中，揭示了主链构象与分子内传导之间的关系。在这项研究中，我们指出动态电双折射光谱是研究导电聚合物的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.