Microscopic Analysis of Inherent Void Passivation in Perovskite Solar Cells

The presence of voids in perovskite solar cells influences the efficiency because of accelerated charge recombination. The induced electric field near voids due to band bending attracts photogenerated electrons and holes toward the voids, leading to carrier recombination. However, if the surface of the voids is coated by materials with a band gap higher than that of the perovskite layer, the strong electric field induced near the voids in the opposite way prevents carriers from recombining. We identified voids in the perovskite layer by using an electron beam-induced current technique and found the influence of field-assisted passivation by organic materials on the efficiency of the solar cell.