Interfacial interactions and properties of lead oxysalts passivated MAPbI3 perovskites from first-principles calculations

The relationship between the structure and properties of the PbSO4/MAPbI3 and PbCO3/MAPbI3 interfaces was investigated via density functional theory (DFT) and non-equilibrium Green’s function (NEGF) calculations. [Display omitted] •The interaction between lead oxysalts and CH3NH3PbI3 are characterized by DFT and NEGF calculations.•Strong orbital hybridization account for the interfacial stability enhancement.•The formations of Pb-O bonds passivate the defect states and improve the charge extraction efficiency.•The PbSO4 capping layer has better effect on improving the interfacial stability than PbCO3. The stability issue of organohalide lead perovskites in humid conditions is a key challenge to their commercial application in the photovoltaic field. In this study, density functional theory (DFT) and non-equilibrium Green’s function (NEGF) calculations were employed to clarify the interfacial interactions and properties between the perovskite and its lead oxysalt passivation layers. It was found that internally-generated electric fields form at the interfaces and the photoexcited electrons transfer from the perovskite to the lead oxysalts side. The strong orbital hybridization at the interface accounted for electron-hole excitations, interface reconstruction, electron redistribution, and stability enhancement. Most importantly, the lead oxysalt-capped MAPbI3 was found to be capable to withstand the reaction with atomic oxygen through passivating the under-coordinated anions. Theoretical studies reveal that the introduction of lead oxysalts can effectively protect MAPbI3 from erosion. These findings illustrate the passivation mechanism of lead oxysalts to stabilize the efficiency of perovskite photovoltaic devices.