Effects of chlorine addition to perovskite-type CH3NH3PbI3 photovoltaic devices

Abstract

Effects of PbCl2 addition to perovskite CH3NH3PM3 precursor solutions on the photovoltaic properties were investigated. TiO2/ CH3NH3PbI3-xClx-based photovoltaic devices were fabricated, and the microstructures of the devices were investigated by X-ray diffraction. The structure analysis indicated phase transformation of the perovskite structure from cubic to tetragonal system by chlorine (Cl)-doping. External and internal quantum efficiencies were improved by a small amount of Cl-doping, which resulted in improvement of the efficiencies of the devices. This would be due to preservation of the cubic CH3NH3PbI3-xClx structure, and to expansion of energy gap and diffusion length of exitons by Cl-doping at the iodine sites.