LAUSR

For the fabrication of perovskite solar cells (PSCs) using a solution process, it is essential to understand the characteristics of the perovskite precursor solution to achieve high performance and reproducibility. The colloids (iodoplumbates) in the perov-skite precursors under various conditions were investigated by UV-visible absorption, dynamic light scattering, photolumines-cence, and total internal reflection fluorescence microscopy techniques. Their local structure was examined by in-situ X-ray absorption fine structure studies. Perovskite thin films on a substrate with precursor solutions were characterized by transmis-sion electron microscopy, X-ray diffraction analysis, space-charge-limited current, and Kelvin probe force microscopy. The colloidal properties of the perovskite precursor solutions were found to be directly correlated with the defect concentration and crystallinity of the perovskite film. This work provides guidelines for controlling perovskite films by varing the precursor solu-tion, making it possible to use colloid-engineered lead halide perovskite layers to fabricate efficient PSCs.