Trimming defective perovskite layer surface boosts the efficiency for inorganic solar cells

Abstract

Inorganic perovskites have attracted much attention due to their excellent photothermal stability. However, the elevated density of surface defect states limits further improvements of the efficiency. Here, we demonstrate a surface defect trimming (SDT) strategy to enhance device photovoltaic performance. In brief, surface defects are eliminated by the synergistic action of methanol solvent and 1, 3-diaminoguanidine monohydrochloride (DGMC). The amino group of DGMC interacts with Halogen ion via hydrogen bonding and with Pb²⁺ via Lewis base–acid coordination bonds. also plays the role of in-situ passivation of defects. The surface reconstruction was realized in the process of secondary annealing. The surface defect state density is trimmed and the work function is well matched with the transport layer. Consequently, the inverted device based on SDT strategy achieves 20.20 % power conversion efficiency (PCE) and record 85 % fill factor (FF) in the full ambient air.