Structure of Organometal Halide Perovskite Films as Determined with Grazing-Incidence X-Ray Scattering Methods

Grazing-incidence X-ray scattering (GIXS) methods have proven to be a valuable asset for investigating the morphology of thin films at different length scales. Consequently, GIXS has been applied to the fast-progressing field of organometal halide perovskites. This exciting class of materials has propelled research in the areas of cheap and sustainable photovoltaics, light emitting devices, and optoelectronics in general. Especially, perovskite solar cells (PSC) have seen a remarkable rise in power conversion efficiencies, crossing the 20% mark after only five years of research. This research news outlines GIXS studies focusing on the most challenging research topics in the perovskite field today: Current-voltage hysteresis, device reproducibility, and long-term stability of PSC are inherently linked to perovskite film morphology. On the other hand, film formation depends on the choice of precursors and processing parameters; understanding their interdependence opens possibilities to tailor film morphologies. Owing to their tunability and moisture resistance, 2D perovskites have recently attracted attention. Examples of GIXS studies with different measurement and data analysis techniques are presented, highlighting especially in-situ investigations on the many kinetic processes involved. Thus, an overview on the toolbox of GIXS techniques is linked to the specific needs of research into organometal halide perovskite optoelectronics.