Effect of surface composition on electronic properties of methylammonium lead iodide perovskite

Methylammonium lead iodide perovskite, CH3NH3PbI3, is one of the most promising photovoltaic materials for low-cost and clean source of energy. In this work, the first-principles calculations were carried out to investigate the different composition of CH3NH3PbI3 (001), including both methylammonium iodide terminated (MAI-T) and PbI2 terminated (PBI2-T) surfaces. The calculated surface energies show that the MAI-T is thermodynamical more stable than the PBI2-T one under the equilibrium growth condition. The electronic properties of the two types of surfaces are also different. The band gap of PBI2-T is obviously smaller than that of MAI-T due to the surface Pb states. Band gaps of MAI-T decrease with increasing thickness, while band gaps of PBI2-T are insensitive to the slab thickness. The calculated optical absorption coefficients suggest that both terminations are effective solar energy absorbers in the visible light spectrum. (C) 2015 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.