Beneficial Role of Organolead Halide Perovskite CH3NH3PbI3/SnO2 Interface: Theoretical and Experimental Study.

Understanding the interfacial properties of perovskite/SnO2 interface is important for perovskite solar cell design and optimization. Here, interfacial structure and transport properties of CH3NH3PbI3/SnO2 interfaces are investigated comprehensively by density functional theory and experiment. Forming CH3NH3PbI3/SnO2 interfaces weakens the gap states induced by CH3NH3PbI3 surfaces. The interfacial transport properties are strongly dependent on the interface atomic configurations. The CH3NH3PbI3/SnO2 interface with PbI and O terminations is more beneficial for hole blocking and electron transporting due to the largest valence band offset compared to the CH3NH3PbI3/SnO2 interface with other terminations. Moreover, it exhibits a larger electrostatic potential difference compared with CH3NH3PbI3/TiO2 interface, leading to the higher electron transfer efficiency. Hence, higher power conversion efficiency is achieved based on CH3NH3PbI3/SnO2 compared to CH3NH3PbI3/TiO2 structure in experiments. In addition, CH3NH3PbI3/SnO2 interfaces with PbI terminations are more stable than those with CH3NH3I terminations, suggesting PbI2 layer may be preferentially formed on SnO2 substrate during CH3NH3PbI3 fabrication process. Such results could provide a useful understanding on CH3NH3PbI3/SnO2 interface and contribute to new strategies for the interface optimization. [ABSTRACT FROM AUTHOR]