基于多元复合钙钛矿单晶膜的高效钙钛矿单晶太阳能电池研究

Perovskite single crystals have superior photoelectric properties than polycrystalline thin films. To fabricate high-performance monocrystalline perovskite solar cells is one of the key scientific issues in the field of perovskite photovoltaics. However, the lack of growth method for perovskite single crystal thin films on desired substrate hinders the development of monocrystalline perovskite solar cells. This project devotes to developing the diffusion-facilitated space-confined lateral growth method to prepare perovskite single crystal thin films on the titania surface, constructing novel high-performance monocrystalline perovskite solar cells adopting mixed-cation/mixed-halide monocrystalline perovskite active layer, and investigating the performance loss mechanism of monocrystalline perovskite solar cells. Firstly, the space-confined lateral growth method will be developed to prepare thickness controllable perovskite single crystal films in the micron scale on self-assembled monolayer modified titania surface. Then, the influence of perovskite film thickness, surface defect passivation and device structure on the cell performance will be investigated. Further, we will study the potential application of monocrystalline perovskite solar cells on promoting the efficiency of large area device and extending the durability of perovskite solar cells. Finally, the physical image of the loss mechanism for monocrystalline perovskite solar cells will be established via spectroscopic study of the perovskite material and titania/perovskite interface, and this will further be used to optimize the cell design and fabrication. This project is proposed to enrich the preparation and characterization method of monocrystalline perovskite solar cells, and to provide theoretical and technical support to design high performance perovskite solar cells.

钙钛矿单晶具有显著优于多晶的光电性质，发展钙钛矿单晶太阳能电池是钙钛矿光伏领域的一个关键科学问题。但由于缺乏在目标基底上制备超薄钙钛矿单晶膜的方法，阻碍了钙钛矿单晶电池的发展。本项目致力于发展扩散辅助的空间限域侧向生长法，在二氧化钛表面上生长多元复合钙钛矿单晶膜，制备高效的正装结构钙钛矿单晶太阳能电池，并对其进行失效机制研究。首先，通过自组装单分子层提高二氧化钛表面钙钛矿前驱体的平面内扩散速度，在微米级空间间隔内生长连续的钙钛矿单晶膜；然后，探索单晶膜厚度、单晶膜表面缺陷钝化、平面/介孔型器件结构对电池性能的影响，并研究单晶钙钛矿电池在大面积器件和提高电池稳定性上的潜在优势；最后，对单晶电池中的钙钛矿材料、二氧化钛/钙钛矿界面进行谱学研究，构建电池的失效机制图像，反馈并优化器件的设计。通过本项目研究，拓展钙钛矿单晶电池的制备和表征方法，为进一步设计高性能钙钛矿太阳能电池提供理论和技术支持。

钙钛矿是离子化合物半导体，通过常规溶液法制备的钙钛矿含有丰富的晶体缺陷，这些缺陷是制约钙钛矿太阳能电池的效率提升和工作稳定性的关键因素。如何降低钙钛矿太阳能电池中的缺陷浓度是本领域的关键科学问题。本项目探索了扩散辅助的空间限域法生长钙钛矿单晶，并将钙钛矿单晶应用于诱导具有准单晶特征的钙钛矿薄膜的生长，制备高性能钙钛矿太阳能电池，并研究其长效稳定机制。本项目还通过调控钙钛矿的化学组成、结晶生长、晶格和表面缺陷，以及钙钛矿/电子传输层界面的质量，制备具有准单晶特性的高效率高稳定性钙钛矿太阳能电池，并研究其失稳机制。取得的主要成果如下：1）成功地在亲水性的电子传输基底上制备了钙钛矿单晶膜；2）发展了钙钛矿/钙钛矿单晶晶种法制备具有准单晶特征的钙钛矿太阳能电池；3）实验室钙钛矿太阳能电池的效率实现大幅提升，从此前的低于20%提升到23.3%；4）研究了具有准单晶特征的钙钛矿太阳能电池的失效机制，发现其工况稳定性依赖于钙钛矿中的初始缺陷浓度，并发现钙钛矿太阳能电池在工作过程中的钙钛矿/电子传输层界面降解和钙钛矿体相由于失去有机阳离子降解为碘化铅是导致其失稳的重要原因。本项目的实施为设计和制备高性能钙钛矿太阳能电池提供了基础参考。