Revealing the microstructures of metal halide perovskite thin films via advanced transmission electron microscopy

Metal halide perovskites (MHPs) are excellent semiconductors that have led to breakthroughs in applications in thin-film solar cells, detectors, and light-emitting diodes due to their remarkable optoelectronic properties and defect tolerance. However, the performance and stability of MHPbased devices are significantly influenced by their microstructures including the formation of defects, composition fluctuations, structural inhomogeneity, etc. Transmission electron microscopy (TEM) is a powerful tool for direct observation of microstructural at the atomicscale resolution and has been used to correlate the microstructure and performance of MHPbased devices. In this review, we highlight the application of TEM techniques in revealing the microstructures of MHP thin films at the atomic scale. The results provide critical understanding of the performance of MHP devices and guide the design of strategies for improving the performance and stability of MHP devices.