Multimodal microscopy characterization of halide perovskite semiconductors: Revealing a new world (dis)order

Halide perovskites are enabling a variety of high-performance devices, yet these materials exhibit heterogeneity in their chemical, structural, morphological, and optoelectronic properties on different length scales. A global understanding of the relationship between these properties, and how they evolve under operation, is essential for commercialization. This perspective covers efforts to attain such relationships through multimodal and correlative microscopy. A variety of ex situ, in situ, and operando measurements have led to key conclusions that the length scales that are extremely important-yet least understood-are on the grain, sub-grain, and atomic scales. The multifaceted disorder of these materials and their ionic nature make complete characterization challenging, but exploitation of the latest experimental probes is stretching our knowledge, allowing rational approaches to improve performance and stability. Future adaptions will employ machine-learning-driven algorithms to process large hyperspectral datasets and operando measurements on the manufacturing line, in turn refining processing and device architectures.