Anomalous Growth and Coalescence Dynamics of Hybrid Perovskite Nanoparticles Observed by Liquid-Cell Transmission Electron Microscopy.

We report on in situ observations of nucleation, growth, and aggregation of hybrid organic-inorganic perovskites by liquid-cell transmission electron microscopy. Direct crystallization of hybrid CH3NH3PbI3 nanoparticles is achieved through an electron beam-assisted solvent evaporation approach. Time-lapse liquid-cell TEM imaging of the nanoparticles reveals a growth trend which is not entirely consistent with the classical Lifshitz-Slyozov-Wagner growth model. Significantly complex dynamical behaviors are observed during the coalescence process of CH3NH3PbI3 nanoparticles. We propose that the chemical instability inherent in the hybrid perovskite iodides should be considered to understand this phenomenon in addition to the oriented attachment mechanism. This study provides a useful reference for understanding the intriguing chemical and physical properties of hybrid organic-inorganic perovskites.