Formation of Semiconducting Polymer/Inorganic Semiconductor Nanointerface and the Electrical and Optical Study toward ETA Solar Cell

无机半导体纳米颗粒具有与块状材料相比具有极大面积的多孔表面。该特性已应用于使用纳米多孔TiO_2的湿染料敏化太阳能电池。染料敏化太阳能电池的固化问题是染料敏化太阳能电池应用中面临的问题之一。TEA（极薄吸收剂）型太阳能电池是固态太阳能电池的候选材料，其性能取决于TiO_2与p型半导体之间的p-n结处染料的光诱导电荷分离。由于光伏性能严重依赖于复杂的异质结界面，因此阐明异质结界面的特征具有重要意义。在本研究中，研究了由纳米多孔TiO_2/半导体聚合物异质结组成的双层器件的光伏性能。作为半导体聚合物，采用了聚噻吩和聚硅烷。在周期性光照射下，用光伏法观察了其光伏性质。电池的光伏特性在很大程度上取决于测量中的大气。真空光照射过程中电池的原位差分光谱显示，近红外区被捕获的载流子的宽吸收带增加，这是开路电压降低的原因。从MO计算、拉曼光谱和荧光光谱等方面讨论了载流子捕获的机理。

The inorganic semiconductor nanopaticles have a porous surface with an extremely large area compared to bulk materials. The feature has been applied to a wet dye-sensitized solar cell using a nanoporous TiO_2. One of the problems in the application is the development of the solidification of the dye-sensitized solar cell. The TEA (Extremely Thin Absorber)-type solar cell is a candidate for the solid-state solar cell, which depends on the photo-induced charge separation of a dye at the p-n junction between TiO_2 and p-type semiconductor. The elucidation of the features of the heterojunction interface is important because the photovoltaic properties are seriously depends on the complicated heterojunction interface. In this study, the photovoltaic properties of a two-layer device consisting of nanoporous TiO_2/semiconducting polymer heterojunction were investigated. As semiconducting polymers, polythiophene and polysilanes were adopted. The photovoltaic properties were observed by photovoltammetry under periodic photoirradiation. The photovoltaic properties of the cell significantly depend on the atmosphere in the measurements. The in-situ difference spectra of the cell during photoirradiation in vacuo show the increase of a broad absorption band attributed to trapped charge carriers in the near-IR region, which is the origin of the decrease of the open-circuit voltage. The mechanism of the carrier trapping was discussed on the MO calculation, Raman and fluorescence spectra.