Transmission Electron Microscopy of Halide Perovskite Materials and Devices

The recent rise of halide perovskites (HPs) has revolutionized solar cells and (opto)electronic device research. Numerous studies have implied that structural and compositional characteristics of HPs at various length scales govern the device performance, but much remains poorly understood. In this context, transmission electron microscopy (TEM) has emerged as a powerful characterization tool to accelerate our fundamental understanding of HP materials and devices, with the potential of having a significant impact on the development of HP-based solar cells and (opto)electronic devices. This perspective discusses the important unsolved materials-science problems surrounding HPs and the few available examples of TEM studies of HP materials and devices in the literature. It also highlights the urgency of application of TEM-based techniques for tackling these unsolved issues. Further research in this direction is crucial for advancing the science in the increasingly important HP materials and devices field. Transmission electron microscopy (TEM)-based techniques are uniquely suited for site-specific structural and analytical characterization of halide perovskites (HPs) at atomic, nanometer, and micrometer length scales. TEM-based studies hold the key to understanding the nature and functionality of these fascinating materials that are at the heart of emerging solar cells and (opto)electronic devices. While TEM-based techniques have made several groundbreaking discoveries that have resulted in astonishing advancements in the field of materials science in general over the past decades, their application to HPs has been relatively sparse. Here, we provide a perspective on TEM-based studies of HPs that have been conducted so far and project a vision for how these powerful characterization techniques can be brought to bear on research problems in the field of HPs. An outlook discussing important challenges and opportunities that lay ahead is also presented. Transmission electron microscopy (TEM)-based techniques are uniquely suited for site-specific structural and analytical characterization of halide perovskites (HPs) at atomic, nanometer, and micrometer length scales. TEM-based studies hold the key to understanding the nature and functionality of these fascinating materials that are at the heart of emerging solar cells and (opto)electronic devices. While TEM-based techniques have made several groundbreaking discoveries that have resulted in astonishing advancements in the field of materials science in general over the past decades, their application to HPs has been relatively sparse. Here, we provide a perspective on TEM-based studies of HPs that have been conducted so far and project a vision for how these powerful characterization techniques can be brought to bear on research problems in the field of HPs. An outlook discussing important challenges and opportunities that lay ahead is also presented.