摘要
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 fabri- cation 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-in- organic perovskite thin-films. Through precise control of the perovskite growth conditions the spacing of heteroge- neous 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 exceed- ing 100 pm in diameter. However, no beneficial correlation was found between the size of these well-oriented grain-clus- ters 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.
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.
基金
the financial support from the Australian Renewable Energy Agency (ARENA)
the Australian Centre for Advanced Photovoltaics (ACAP)
the ARC Centre of Excellence in Exciton Science
