Low-dose transmission electron microscopy study on halide perovskites: Application and challenges

Transmission electron microscopy (TEM) is widely used in the materials science community because of its high spatial, temporal and energy resolution. However, for electron beam-sensitive halide perovskites (HPs), the achievements offered by TEM are still in their infancy due to the nonnegligible structural damage caused by the incident electron beams to the fragile structure. Despite these challenges, the potential for TEM to provide unique insights into the microstructure and phase evolution of HPs at the atomic scale, to track the dynamic ion migration behaviors, and to explore the effects of lattice defects on physicochemical properties is still fascinating. In this review, we summarize recent achievements in HPs through advanced analytical methods embedded in the TEM, including high-resolution/scanning TEM (HRTEM/STEM) imaging, electron diffraction (ED) analysis, X-ray energy dispersive spectroscopy (EDS), and electron energy-loss spectroscopy (EELS) measurement, and in-situ TEM observation, with the aim of providing a multi-dimensional and multi-scale understanding of the intrinsic properties of HPs that have not yet been discovered. In addition, we delve into the inherent beam-damage mechanisms affecting the delicate HPs crystal, thereby emphasizing the significant hurdles associated with employing TEM in HPs research. Finally, we present a number of effective strategies that may be beneficial in reducing the damage caused by beams. In particular, the introduction of a direct-detection electron-counting (DDEC) camera has contributed significantly to the advancement of low-dose imaging and the suppression of beam damage to the intrinsic structure of HPs. With the improvement of low-dose imaging technology, TEM characterization is expected to promote a comprehensive understanding of the intrinsic properties of HPs in terms of structure-property-performance and to expand the wide range of applications of HPs in optoelectronic devices.