Composition-controlled organometal halide perovskite via CH3NH3I pressure in a vacuum co-deposition process

Abstract

We report an efficient method to adjust the compositions of CH₃NH₃PbI₃ perovskite by controlling the working pressure of CH₃NH₃I and its effects on perovskite films in a vacuum co-deposition process. Thermal heating of the CH₃NH₃I source in a vacuum chamber increases the working pressure, which can be an indicator for the control of the ratio of CH₃NH₃I for the perovskite in the vacuum thermal co-deposition process. Under different working pressures, the physical properties of the films with various compositions differed significantly. At the optimum working pressure, the perovskite solar cell fabricated using an all-vacuum process showed a maximum power conversion efficiency of 14.5% with high reproducibility, implying successful formation of the film using the pressure-controlled vacuum co-deposition.