Determining ultrafast carrier dynamics of hybrid perovskites at various stages of nucleation and growth kinetics

With hybrid organic-inorganic perovskites increasing its technological reach, from photovoltaics solar cells to light-emitting devices, to nanoscale transistors, it is critical to establish the role of microstructures in dictating how carrier dynamics dictate device efficiency. Here we report on the ultrafast dynamics of charge carriers in hybrid perovskites at various stages of nucleation and growth kinetics. A solution-processed fabrication technique, with spin-coating conditions optimized to control the nucleation density of an intermediate phase, converts to hybrid perovskites upon a temperature gradient annealing. This strategy decouples the nucleation and growth steps that lead eventually to large-grain thin films, allowing us to probe electronic and carrier dynamic differences. We find, surprisingly, that the nucleating microcrystals already display the electronic properties of hybrid perovskites and share similar femtosecond-to-nanosecond dynamics as large-grain hybrid perovskite thin films.