高质量硫化物钙钛矿BaZrS3薄膜的低温制备与光电性能调控机制研究

由于具有直接带隙、高吸收系数、高稳定性和组成元素丰度高等独特优势，硫化物钙钛矿半导体BaZrS3(钡锆硫)被视为一种富有创新性的吸收层材料，在制备下一代高稳定性和高效率太阳能电池方面具有广阔的前景。然而受限于硫化反应中高活化能和易出现杂质等因素，目前尚无法在低温下生长高质量BaZrS3薄膜，更缺乏理论机制和实际方案调控优化其光伏特性。本项目拟计划将高温条件限制在BaZrS3粉末和靶材制备过程，然后在磁控溅射中引入高活性射频硫源弥补调控硫缺失，从而实现在低温下(<400℃)生长具有良好结晶性、均一性、致密性BaZrS3薄膜。进一步阐明薄膜中缺陷态-光电特性的关联机制，通过优化化学计量比等方案抑制深能级缺陷并提升载流子扩散长度，最后借助非平衡生长条件在BaZr1-xTixS3合金中形成单一相亚稳态畸变钙钛矿结构从而调控其禁带宽度，为制备高稳定和高效率硫化物钙钛矿光伏器件奠定基础。

Due to its unique advantages like direct band gap, high absorption, stability and abundance, sulfide perovskite semiconductor BaZrS3 is regarded as one of the most innovative materials acting as the absorption layer, therefore has broad prospects in the fabrication of next-generation solar cells with high stability and efficiency. However, limited by the high activation energies and high content of impurities in sulfurization reactions, growth of high quality BaZrS3 thin films at low temperatures has not been realized. Moreover, the theoretical mechanism and practical methods of tailoring and optimizing photovoltaic properties are absent. This project proposes to limit the high processing temperatures in the process of BaZrS3 powders synthesis and target fabrication. Furthermore, by introducing reactive RF sulfur sources to compensate sulfur loss in sputtering, growth of BaZrS3 thin films with high crystallinity, homogeneity and compactness at low temperatures (<400℃) can be achieved. This project will also investigate the relationship between defects and the optoelectronic properties, then try to suppress the defects and increase the carrier transport length through methods like optimizing the stoichiometry. At last, band gaps will also be tuned in single phase BaZr1-xTixS3 alloys with metastable distorted perovskite structure, which can be stabilized under non-equilibrium growth conditions. This work helps to lay the foundations for the fabrication of high stable and efficiency sulfide perovskite solar cells.