Surface Doping of Sn in Orthorhombic CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf>for Potential Perovskite Solar Cells: First Principles Study

Abstract

© 2016 Elsevier B.V. We employed the density functional theory (DFT) based on plane wave pseudopotential method to investigate the structural and optical properties of Sn-incorporated orthorhombic CH3NH3PbI3, especially surface doping. The results from formation energies and chemical potential diagrams indicate that the condition defined between Pb-rich and I-rich is the most suitable condition to incorporate Sn into CH3NH3PbI3structure because formation energy of the impurity structure is lower than that of the undoped surface structure. Consequently, Sn doping can also stabilize surface structure. We found that the substitution of Sn for Pb atom on CH3NH3PbI3surface significantly reduces Egby 0.24 eV, compared with that of bulk doping. Therefore, the impurity of Sn on CH3NH3PbI3surface displays better improvement of optical properties and allows the perovskite to absorb light in a wider range (near-IR region) of wavelength in solar radiation.