Studies on Conduction Mechanisms for Alternating Polymers Composed of Organosilicon and π-Electron Units and Application to Functionality Materials

本研究的主要兴趣在于阐明主链上有机硅单元和π电子系统交替排列的聚合物的传导机制，并研究其作为功能材料的利用。在这些观点下，合成了以单硅炔（MS）、二硅炔（DS）、三硅炔（TS）为单元的聚合物和低聚噻吩π体系（mT）及其相关聚合物。交替Si-mT聚合物在FeCl_3气相掺杂下表现出10^<-4> - 10^<-1> S/cm的电导率水平，MS-5T在电化学掺杂/脱掺杂时表现出高度稳定。作为电致发光器件的空穴传输材料，这些聚合物具有优异的电流发光特性。采用MS-mT方法研究了以下几点：(1)极化子、双极化子和π-二聚体在导电机理中的作用；(2)链内路径和链间路径之间的主导路径；(3)金属导电演变的原因。结果表明，在轻掺杂状态下，链间跳变是载流子输运的主要途径，π二聚体是这些聚合物的主要输运途径。还制备了区域规整度分别为97%、81%、70%和54%的聚己基噻吩（PHT）。为了阐明聚合物链的堆叠对导电聚合物输运性质的影响，对这些pht薄膜中载流子的迁移率进行了电化学和光谱评价，并将其作为掺杂水平的函数。结果表明：(1)有序的堆垛结构增强了迁移率，但对掺杂对迁移率变化的影响不大；(2)极化子的链间跳输运是轻掺杂聚合物中主要的导电路径；(3)噻吩平面的堆积与金属感应的演化无关，但对载流子的迁移率有很大影响。

The main interest of this research is placed on clarification of conduction mechanisms for polymers with alternating arrangement of an organosilicon unit and π-electron system in the main chain and also on utilization of the polymers as functionality materials. In these viewpoints, polymers with the monosilanylene (MS), disilanylene (DS), or trisilanylene (TS) unit and oligothiophene π-system (mT), and the related polymers moreover, were synthesized. The alternating Si-mT polymers exhibited a 10^<-4> - 10^<-1> S/cm level of conductivity on doping with FeCl_3 vapor, and MS-5T was found to be highly stable upon electrochemical dopirig/dedoping. These polymers exhibited excellent current-luminance characteristics as the hole-transporting materials of EL devices.The following points have been investigated by using MS-mT: (1) the role of polaron, bipolaron, and π-dimer in conduction mechanism; (2) dominating path between intrachain and interchain paths; (3) reason for the evolution of metallic conduction. It is concluded that in the lightly doped state, interchain hopping is the main path for carrier transport, and π-dimers concern in these polymers.Polyhexylthiophenes (PHT) with different regioregularity of 97%, 81%, 70%, and 54% were also prepared. In order to clarify influences of stacking of polymer chains on the transport properties of conducting polymers, the mobilities of charge carriers in the films of these PHTs were electrochemically and spectroscopically evaluated as the function of doping level. The results clearly show that (1) better ordered stacking structures enhance mobilities but affect little features of the mobility change by doping; (2) the interchain hopping transport of polarons is a dominating path of the electrical conduction in the ightly doped polymer; (3) stacking of thiophene planes is not associated with the evolution of metallic induction, although it greatly affects mobility of charge carriers.