Effect of cuprous iodide passivation in perovskite solar cells

Perovskite solar cells have become a very researchable topic because of their interesting properties and very high-power conversion efficiency. Defects in the absorber layer are the origin of trap-states and hinder the power conversion efficiency of perovskite solar cells in approaching the Shockley–Queisser limit. Here, P–I–N structured devices were fabricated and passivated using Cuprous iodide. The effect of passivation was analyzed by studying the charge carrier concentration and characteristics. Passivation imparts lowering of defects in the bandgap that was observed by the difference in photoluminescence counts and drop in Urbach energy by ~ 24%. This lowered defect will give rise to lower recombination in the active material. The effect of altering the defects was demonstrated by the device performance by various material and electrical characterizations. Lowering of the defect levels has been established from the power conversion efficiency enhancement of 18.5% along with lowering of hysteresis has been observed for passivated devices. The role of defects in the device performance and the change in device parameters have been investigated with varying defect concentrations of different types of defects using SCAPs-1D simulation software.