Antiseptic Povidone–Iodine Heals the Grain Boundary of Perovskite Solar Cells

Povidone, also know as polyvinylpyrrolidone (PVP), is used as a reservoir for iodine, and the povidone-iodine (PVP-I) complex has antiseptic properties for wound healing by releasing iodine. In this report, we utilized this unique characteristic of PVP-I to heal the photovoltaic parameters of perovskite solar cells (PSCs). PVP-I was added in the perovskite precursor solution, where the effect of the PVP-I concentration on the photovoltaic performance was investigated. The power conversion efficiency (PCE) of PSC was enhanced from 20.73% to 22.59% by addition of 0.1 mg/mL PVP-I, mainly due to an improved fill factor from 0.76 to 0.80 together with a slight increase in current density. Scanning electron microscopy revealed that the grain boundaries were passivated by PVP-I. Conductive atomic force microscopy combined with time-resolved photoluminesence and space charge-limited current studies showed that the addition of PVP-I decreased the defect density of the perovskite film together and enhanced the film conductivity. Furthermore, better stability was observed from the PVP-I-treated PSCs than the control device without the additive, which is probably owing to the grain boundary healing effect.