铜锌锡硫硒薄膜吸收层的金属有机溶液旋涂法制备及其光电性能研究

In recent years, low toxic, cheap copper-zinc-tin-chalcogenide (herein denoted as CZTSSe) become a research hotspot of the next generation thin film solar cells with low cost and high efficiency, because of its near-optimum direct bandgap, high absorption coefficient, and friendly environment, naturally abundant elemental constituents. Contraposing that the conventional preparation methods of CZTSSe involve toxic hydrazine solvent, and nanocrystalline particles (nano-ink coating method) in the subsequent secondary growth, and composition segregation and uncontrollable phase structure in selenization process, the project proposes the controlled synthesis of Cu2ZnSnS4 (CZTS) precursor film by a low cost, low-toxicity and non-vacuum based metal-organic solution process , and the preparation of CZTSSe absorption layer obtained directly by high temperature selenization of the CZTS precursor film.The influence of the preparation process conditions on the composition, phase structure and microstructure of CZTSSe film is systematically studied, the factors affecting the photoelectric and transport properties of CZTSSe film and its devices are also analyzed，and the impact of the composition, phase structure, microstructure, interface and surface phase behavior and high temperature passivation mechanism of the film on the perfor-mance of CZTSSe solar cell are also discussed in order to optimize the preparation process conditions, and to reveal the mechanism of photoelectric properties. This can offer technical support and theoretical basis for development and application of CZTSSe thin film solar cells.

低毒廉价的Cu-Zn-Sn-硫族化物，简称CZTSSe因其直接带隙与太阳辐射匹配性好、光吸收系数高和环境友好等优点, 近年来成为下一代高效低成本太阳电池研究热点。针对常规CZTSSe制备方法中存在有毒的肼溶剂和纳米晶颗粒（纳米墨汁涂覆法）在后续硒化处理中的二次生长及组分偏析和薄膜相结构不易控制的问题，本项目拟采用一种非真空、低成本无毒的金属有机前驱体溶液旋涂法制备成分可控的Cu2ZnSnS4（CZTS）前驱膜，并利用高温硒化工艺从有机前驱体膜直接生长成大尺度晶体CZTSSe吸收层。系统地研究其制备工艺参数对CZTSSe薄膜成分、相结构、微结构影响；同时，分析影响CZTSSe薄膜及其太阳电池光电和输运性能的因素，并探索其成分、相结构、微结构、界面表面相行为及高温钝化机制对太阳电池性能的影响，从而优化工艺条件，揭示其光电特性机理。以便为CZTSSe薄膜电池的研发和应用提供技术支持和理论依据。

低毒廉价的Cu-Zn-Sn-硫族化物作为太阳能电池的关键材料，其光电特性直接影响器件的性能与应用。本项目采用非真空的溶液法制备出了CZTS金属有机前驱体溶液，利用旋涂后硒化工艺制备CZTSSe薄膜吸收层，并同时采用等价阳离子替代方案制备了Ge、Cd和Mg元素部分替代的CZTSSe吸收层，对CZTSSe及其掺杂的CZTSSe吸收层的光电特性进行了深入的实验研究和理论分析。探讨了影响吸收层光电和输运性能的因素，揭示其光电特性机理。通过调节制备工艺能够获得最佳光电性能的CZTSSe薄膜样品，其太阳能电池器件转换效率PEC达到了6.64%。通过等价阳离子掺杂，如Ge对Sn、Cd或Mg元素对Zn的部分替代，能够调节CZTSSe的光学带隙，减少CuZn等缺陷形成，从而提高载流子迁移率，提高薄膜的质量，进而改善薄膜的导电性能和光电特性。其中Mg的微量掺杂能够降低薄膜的表面粗糙度，提高薄膜的表面电流，改善薄膜的电学性能，提高电池器件的光电性能。制备出的Mg掺杂的CZMTSSe的薄膜太阳电池PEC达到了7.76%，相对于未掺杂Mg的CZTSSe薄膜太阳电池的PEC（6.64%）提高了16.9%。此研究为太阳电池吸收层材料的开发与设计提供了新思路，也为进一步CZTSSe薄膜电池的研发和应用提供技术支持和理论依据。