LAUSR

A heightened understanding of nucleation and growth mechanisms is paramount if effective solution processing of organic-inorganic perovskite thin-films for optoelectronic applications is to be achieved. Many fabrication techniques have been utilized previously to develop high-performance perovskite layers but there remains an absence of a unifying model that describes accurately the formation of these materials from solution. The present study provides a thorough analysis of nucleation and growth kinetics underpinning the development of hybrid organic-inorganic perovskite thin-films. Through precise control of the perovskite growth conditions the spacing of heterogeneous nucleation sites was varied successfully from several hundred nanometers to several hundred microns. The crystalline regions surrounding these nuclei were found to comprise clusters of highly-oriented crystal domains exceeding 100 μm in diameter. However, no beneficial correlation was found between the size of these well-oriented grain-clusters and the optoelectronic performance. The formation of the perovskite microstructure features characteristics of both classical and non-classical growth mechanisms. The insights into perovskite thin-film growth developed by the present study provide clear implications for the development of future hybrid perovskite microstructures.摘要如何利用溶液法制备高质量、高效率的有机-无机杂化钙钛矿薄膜光电器件, 取决于对该体系的核化和晶体生长机理的深入研究.尽管用很多方法可以制备出高性能的钙钛矿薄膜, 到目前为止, 还缺乏一个准确且统一的模型, 去解释钙钛矿晶体是如何从溶液中析出生长的过程. 本文通过对晶体核化和生长动力学的详细研究, 提出了有机-无机杂化钙钛矿薄膜材料的形成机制. 通过精准控制钙钛矿晶粒生长的条件, 异质晶核之间的距离能够在几百纳米到几百微米之间调控. 我们还发现在晶核周围直径超过100微米范围, 聚集着取向高度一致的晶体团簇. 但是这些晶体团簇的尺寸大小, 与提高钙钛矿光电器件的性能并没有什么直接的对应关系; 钙钛矿材料微观结构的形成机理,兼有经典和非经典晶体生长的特征. 因此对钙钛矿薄膜生长的深入研究, 将有助于进一步控制杂化钙钛矿薄膜的微观结构.