Effects of Excess PbI2 Addition to CH3NH3PbI3−xClx Perovskite Solar Cells

TiO2/CH3NH3PbI3−xClx-based photovoltaic cells with a small amount of excess added PbI2 were fabricated in ambient air. The fill factor and short-circuit current density were increased, which resulted in improvement of the photovoltaic performance. The recombination between a hole and an electron would be suppressed by the PbI2 formation, and the external quantum efficiencies were increased.