高效有机染料敏化纳米晶三元氧化物太阳能电池

A series of nanostructural ternary oxides will be synthesized and used them as the electrodes for organic dye-sensitized solar cells (DSCs). To obtain nanostrucutral ternary oxides with different energy levels, the ratio of compositions in the ternary oxides will be adjusted or new elements will be introduced into ternary oxide system, resulting in the formation of complex oxides. As a result, the methods of regulation for the energy levels would be established. At the same time, new type organic dyes will also be developed and used as the sensitizers for DSCs. The interaction and energy match between the ternary oxides and new organic dyes will be investigated in detail, and the DSCs with low cost and high efficiency would be achieved. On the other hand, the surface of ternary oxides will be modified with MOF or other materials and the coating layer would be formed, the adsorption ability of dye molecule on the surface of ternary oxides would be improved, the impedance and recombination of charge at the interfaces between the surface of electrode materials and dyes would be decreased, and the highly efficient dye-sensitized solar cells based on ternary oxides would be obtained. Furthermore, the influences of energy variation on the photovoltaic properties will be investigated, the mechanism of electron transport in boundaries among ternary oxide particle, dye molecule, FTO substrate and electrolyte will also be explored. In a word, the present work will contribute to the development of new type electrode materials and novel dye molecule, the photovoltaic performances of DSCs will also be enhanced. At the same time, new materials with an independent intellectual property for photo-to-electricity energy conversion would be developed.

围绕着获得具有自主知识产权的光电转换材料体系，设计合成系列三元半导体氧化物，利用其光稳定性，并结合有机染料分子的特性，研制出高效率、低成本、长寿命和环境友好的有机染料敏化三元氧化物太阳能电池(DSC)。基于三元半导体氧化物的能级可调控特性，通过导入金属离子，实现掺杂和改变能级，并构建其能级调控体系。同时，研究三元半导体氧化物和宽吸收光谱有机染料分子之间的相互作用，实现电极材料与染料分子之间的能级最佳匹配，以提高电池的光电性能。进一步，利用金属有机框架(MOF)等材料对三元氧化物电极表面进行修饰，以提高吸附染料能力、抑制电荷复合、优化DSC的构成和改善光电性能，实现DSC的高效率化。进而揭示三元氧化物的能级变化、表面修饰等对DSC光电性能影响的规律，阐明电子输运机理和电荷复合机制，为提高DSC的光电性能提供新的研究思路和设计合成新型多元氧化物电极材料奠定理论基础，具有重要的学术和实用意义。

本项目围绕着获得具有自主知识产权的光电转换材料体系，设计合成系列三元半导体氧化物和有机染料分子，通过调控和匹配它们的能级，研制高性能的有机染料敏化三元氧化物太阳能电池。首先，设计合成系列纯有机染料分子(Phenylene-Thiophene-Phenylene; PSP)，通过在芳胺中引入苯环、甲氧基以及烷基等给电子基团，形成对光吸收较强的大π共轭单元，提高吸收光能力(300-600nm)。同时，设计合成系列三元半导体氧化物，并通过金属离子掺杂等手段，实现三元氧化物能级的变化。例如，Zn2SnO4中引入Ba2+/Sr2+，实现能级调控。但是，随着掺杂量的增加，Zn2SnO4的费米能级与电解液中氧化还原电位之差减小，导致开路电压减小。进一步，利用本项目中合成的三元氧化物和有机染料组装电池，开展了光电性能的研究，并探索三元氧化物与有机染料分子之间的能级匹配，从而优化器件的组成。例如，改性有机染料N-PSP为敏化剂，Ba2+/Sr2+掺杂Zn2SnO4为电极薄膜组装器件，最高光电转换效率达到4.9%，比N719染料敏化器件的效率高，说明通过三元氧化物和有机染料分子能级匹配的调控，可以提高三元氧化物基电池的性能。基于三元氧化物的特性，本项目中探索其在钙钛矿型太阳电池中的应用。首次把三元氧化物Zn2Ti3O8作为介孔层，使钙钛矿型电池的光电转换效率达到17.21%。这是由于Zn2Ti3O8具有降低的导带位置和较高的价带位置，既有助于提高电子注入动力又可以减少阳极附近电子的反向复合，也就是电子-空穴分离能力强、电子传输更快和电荷复合弱等特性。尤其是，三元氧化物H2Ti3O7作为介孔层不但使最高效率达到17.61% (70块电池的平均光电转化效率高达16.73%)，还能够基本消除I-V曲线的滞后现象，这一发现可为研制高稳定性的钙钛矿型电池提供实验依据。同时，三元氧化物引入钙钛矿太阳能电池中，丰富了介孔层材料体系，也能为电池材料形成合理的能级阶段创造条件，提高电子传输速度和抑制电荷复合，从而改善器件性能。