Metal halide perovskite (MHP) thin films are the main photoactive layer in state-of-the-art perovskite solar cells (PSCs). Due to their polycrystalline nature, MHP films contain grains that typically vary in sizes from several hundreds of nanometers to several micrometers. The processes occurring on the lengths scales of grains are expected to impact the macroscale operation of PSCs. The ability to visualize and understand the behavior of MHPs on the length scales of grains is an important step for fabrication of high-quality PSCs.

In this talk, I will describe how we employ advanced imaging characterization to visualize the behavior of MHPs on the length scales of grains. In particular, I will discuss imaging techniques that enable us to simultaneously assess multiple properties of MHPs, e.g., map surface morphology and probe local chemical composition. I will then show how these imaging capabilities helped us identify undesirable phase impurities in blade-coated MHPs that have potential for large area PSCs. This research will help us control the quality of large area MHPs and will help develop characterization practices that can pinpoint nanoscale roots that can eventually lead to failure of large area PSCs.