Unveiling the Local Fate of Charge Carriers in Halide Perovskite Thin Films via Correlation Clustering Imaging.

As the field of metal halide perovskites matures, a range of compositionally different perovskite films has found a place in efficient optoelectronic devices. These films feature variable local structural stability, carrier diffusion, and recombination, while there is still a lack of easy-to-implement generic protocols for high-throughput characterization of these variable properties. Correlation clustering imaging (CLIM) is a recently developed tool that resolves peculiarities of local photophysics by assessing the dynamics of photoluminescence detected by wide-field optical microscopy. We demonstrate the capability of CLIM as a high-throughput characterization tool of perovskite films using MAPbI (MAPI) and triple cation mixed halide (TCMH) perovskites as examples where it resolves the interplay of carrier diffusion, recombination, and defect dynamics. We found significant differences in the appearance of metastable defect states in these two films. Despite a better surface quality and larger grain size, MAPI films showed more pronounced effects of fluctuating defect states than did TCMH films. As CLIM shows a significant difference between materials known to lead to different solar cell efficiencies, it can be considered a tool for quality control of thin films for perovskite optoelectronic devices.