Growth mechanistic insights into perovskite nanocrystals: dimensional growth†
The optical and electronic properties of lead halide perovskite nanocrystals have been explored extensively due to their increasing demand in photovoltaic and optoelectronic applications. But little is known about the growth kinetics of these nanocrystals. In this work, we demonstrate an interesting new mechanism using the method of arrested growth and precipitation to isolate the intermediates. We find that growth is driven by oriented attachment competing with the surface energetics. Hence, we observe a rare example of self-assembly driven dimensional growth characterized by suitable surface passivation that competes with the exposed surface facets through dimensional growth. This provides an explanation for not only the lack of size and shape tunability but also the emergence of a cubic shape rather than commonly observed spherical shapes in nanocrystals. Additionally, we find that this also corresponds to the observed phase transitions as well as correlating with pathways of decay of the photoluminescence spectra.