A practical guide to Three-dimensional halide perovskites: Structure, synthesis, and measurement

Halide perovskites, a diverse class of crystalline semiconductors, have recently been under intense study by numerous research communities owing primarily to their efficacy as solar-cell absorbers. With this surge in interest has come a plethora of reports, which are challenging to navigate, particularly as a new researcher in the field. Here, we offer a practical guide to the crystal and electronic structures, synthesis, and measurement and characterization of 3D halide perovskites. We do not attempt to provide a comprehensive review of any one topic; instead, we hope to offer the interested researcher who is unfamiliar with the field a tractable entry point into the vast and diverse field of 3D halide perovskites. We start with a brief history and then describe the crystal structure and composition, including multiple subtypes of 3D halide perovskites. We then discuss the electronic structure of 3D halide perovskites, providing both a working understanding of theoretical calculations of perovskite band structures as well as outlining a more intuitive symmetry-based approach that highlights the molecular orbitals that compose the bands. Next, we offer a practical guide to the synthesis of 3D halide perovskites, including some common techniques to prepare both bulk and thin-film samples. We then describe a selection of widely used methods of characterization, giving examples of each as applied to 3D halide perovskites. Finally, we discuss some intriguing properties of 3D halide perovskites to motivate exploratory studies.