用于光阳极散射层的TiO2片层结构的可控合成及光电特性

The photoelectrode scattering layer of dye-sensitized solar cells (DSSCs) need not only possess the large surface area for the more amount of dye loading, but also possess the moderate micirostructure for the photogenerated electron transfer. However, these factors are often incompatible with one another. This proposal plans to fabricate the scattering layer materials of two-dimensional TiO2 plates with large surface area and different microstructure(non porous structure, zero-dimensional porous structure and one-dimensional porous structure) via template method, which is based on the previous obtained two-dimensional graphene (one-dimensional carbon nanotube) and their composite. This different microstructure of TiO2 plates could be controlled by using different template composite structure. Then, the photoelectrode scattering layer will be fabricated by quasi-screen printing. Comparing with the different photoelectrical conversion efficiency of DSSCs with the different TiO2 plate scattering layer, the light scattering (reflection) effect will be systematical researched. Furthermore, the interfacial charge transfer resistance between two-dimensional TiO2 plate scattering layer and redox shuttle, electron transport time and electron diffusion length will be studied by using electrochemical impedance spectra, intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy. At last, the regular results of the influence of the interfacial charge transfer on the photoelectrical efficiency will be obtained. This proposal will explore the new path for high-efficiency photoelectrode scattering layers.

高性能的光阳极散射层不仅要求具有大的比表面积以利于染料的吸附，还要求具有适合的微纳结构以利于光散射和光生电子的传输。但是，通常制备的散射层不能同时满足这些要求。本课题拟在课题组前期完成的二维石墨烯及一维碳纳米管基TiO2复合体的基础上，采用模板法制备大比表面积、不同微结构的二维TiO2片散射层材料，通过控制模板（二维石墨烯及其复合碳材料结构）的组成实现不同微结构（无孔、零维孔和一维孔结构）TiO2片的可控合成。采用类丝网印刷的方法构筑光阳极散射层，通过比较不同形貌、尺寸和比表面积的光阳极散射层的光电转换效率，系统研究其对光的散射（反射）作用，集成运用电化学阻抗和强度调节光电压定量的研究二维TiO2片光阳极散射层与电解液的界面传输电阻、电子传输寿命和电子扩散距离，揭示光阳极散射层-电解液界面电阻对光电效率的影响规律，探索构筑高光电转化效率的二维TiO2片层光阳极散射层的新途径。

染料敏化的纳米晶TiO2光电化学池(DSSCs)因价格便宜、工艺简单、可制成大面积和多形状等优点而成为研究的热点之一,纳米TiO2光阳极是DSSCs的重要组成部分,它决定了染料的吸附量和光生电子的传输速率。高性能的光阳极散射层不仅要求具有大的比表面积以利于染料的吸附,还要求具有适合的微纳结构以利于光散射和光生电子的传输。但是,通常制备的散射层不能同时满足这些要求。本课题以Hummer法制备的氧化石墨为模板,采用溶剂热的方法制备石墨烯/TiO2复合体, 控制石墨烯和钛源的量得到不同含量的复合体;将得到的石墨烯/TiO2复合体依次在H2气氛和空气中烧结,除去石墨烯模板,得到片层结构TiO2;以其为反射层构筑光阳极。研究结果表明:以片层TiO2构筑的光电池的光电转换效率(7.5%)高于通常光电池的转换效率(7.2%)。另外，采用阳极氧化的方法制备了有序TiO2纳米管阵列,通过控制氧化时间和阳极氧化的电解液组成的比例调控制备的TiO2纳米管阵列的长径比。纳米管阵列由于具有很好的光生电子传输特性,是很好的染料敏化太阳能电池光阳极。相关工作探索了构筑高光电转化效率的TiO2光阳极散射层的新途径。