Fabrication of lead halide perovskite solar cells by annealing spin-coated PbI2 thin films in CH3NH3I vapor

Abstract

Lead halide perovskite (CH3NH3PbI3) solar cells possess numerous useful properties, such as appropriate direct bandgaps and high absorption coefficients, and these cells have recently attracted considerable attention owing to their excellent photovoltaic performance and low cost. In this study, perovskite layers intended for use as light-absorbing materials were fabricated by annealing spin-coated PbI2 thin-films in CH3NH3I vapor while assessing the effects of varying the annealing temperature. X-ray diffraction analysis indicated that perovskite began to form at temperatures above 140 °C, with the PbI2 peak completely disappearing above 160 °C. In addition, scanning electron microscopy observations confirmed that the grain size increased with increasing annealing temperature. Solar cells fabricated using perovskite thin-films grown at 140–150 °C for 4 h exhibited a power conversion efficiency of more than 4%.