Physical Passivation of Grain Boundaries and Defects in Perovskite Solar Cells by an Isolating Thin Polymer

Passivation and interlayer engineering are important approaches to increase the efficiency stability of perovskite solar cells. Thin insulating dielectric films at interface between charge carrier transport layers have been suggested passivate surface defects. Here, we analyze effect depositing poly(methyl methacrylate) (PMMA) from a very low-concentration solution. Spatial- time-resolved photoluminescence atomic force microscopy analyses samples with diverse morphologies demonstrate preferential deposition PMMA in topographic depressions layer, such as grain domain boundaries. This treatment results an fill factor more than 4% absolute boost exceeding 1%, maximum 20.4%. Based on these results, propose physical isolation mechanism rather chemical passivation defects, which explains not only data this study but also most found earlier works.