Wang Wenhui, Ghosh Tanmay, Yan Hongwei, Erofeev Ivan, Zhang Kun, Loh Kian Ping, Mirsaidov Utkur
Department of Physics, National University of Singapore, 117551, Singapore.
Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, 117557, Singapore.
J Am Chem Soc. 2022 Oct 5;144(39):17848-17856. doi: 10.1021/jacs.2c06022. Epub 2022 Sep 21.
Organic-inorganic metal halide perovskite films have emerged as potential candidate materials for photoelectric devices because of their superior optoelectronic properties. The performance of these devices depends on the quality of perovskite films defined by their grain size, crystallinity, and absence of pinholes. While solution-based processing is the most cost-effective and scalable approach to producing these films, the impact of the process parameters on the film quality and nanoscale details of these processes are unknown. Specifically, it is unclear how perovskites grow from a liquid precursor to form solid-phase nanocrystals and how these nanocrystals arrange to form a uniform film. Here, using liquid-phase transmission electron microscopy (TEM), we show how perovskite nanocrystals nucleate from a precursor solution and then grow and coalesce to form a polycrystalline film. Furthermore, we show how additives, such as urea, can improve the film crystallinity by increasing perovskite solubility, which induces the dissolution and subsequent redeposition of smaller crystals onto larger grains. Our approach to studying the growth of perovskite films provides an important insight into improving the synthesis of perovskites and other technologically relevant crystalline films.
有机-无机金属卤化物钙钛矿薄膜因其优异的光电性能而成为光电器件的潜在候选材料。这些器件的性能取决于由其晶粒尺寸、结晶度和无针孔所定义的钙钛矿薄膜质量。虽然基于溶液的加工是生产这些薄膜最具成本效益且可扩展的方法，但工艺参数对薄膜质量以及这些工艺的纳米级细节的影响尚不清楚。具体而言，尚不清楚钙钛矿如何从液体前驱体生长形成固相纳米晶体，以及这些纳米晶体如何排列形成均匀的薄膜。在此，我们使用液相透射电子显微镜（TEM）展示了钙钛矿纳米晶体如何从前驱体溶液中形核，然后生长并聚结形成多晶薄膜。此外，我们展示了诸如尿素等添加剂如何通过增加钙钛矿溶解度来提高薄膜结晶度，这会促使较小晶体溶解并随后重新沉积到较大晶粒上。我们研究钙钛矿薄膜生长的方法为改进钙钛矿及其他技术相关晶体薄膜的合成提供了重要见解。
