(171b) In-Situ X-Ray Diffraction Studies on the Self-Assembly of Metal Halide Perovskite Thin Films

Metal halide perovskites (MHPs) are revolutionizing the solar cell research field - the record power conversion efficiency of MHPs based solar cells has reached 22%. This represents the highest efficiency among all solution processable materials and the fastest rate of efficiency improvement in the history of all photovoltaic materials. Based on this trend, MHPs have been called the â??next big thing in photovoltaicsâ? and worldwide research efforts have grown explosively.

Understanding the nucleation and growth processes of the MHP thin films is a prerequisite for scale up of the device area, improvement in reliability and further increase in efficiency. Here we present our results on synchrotron based in-situ grazing incidence X-ray scattering studies on the MHP thin film formation processes. Our results reveal the sub-processes and mechanisms through which highly preferential crystallographic orientation of MHP films can be formed. We demonstrate methods to controllably tune the direction and degree of the preferential orientation. Impact of the degree of thin film orientation on solar cell performance will be discussed.