Electrical transport properties of TiO/MAPbI and SnO/MAPbI heterojunction interfaces under high pressure.

The electrical transport properties of SnO(TiO)/MAPbI (MA = CHNH ) heterojunction interfaces are investigated from ambient pressure to 20 GPa, and the transport properties are calculated by physical parameters such as trap energy density, binding energy, and charge transfer driving force and defect. Based on the partial density of states (PDOS) of the SnO/MAPbI heterojunction interface MAI-termination and PbI-termination, greater charge transfer driving force and higher binding energy are observed, obviously showing the SnO-based heterojunction is more stable. The SnO/MAPbI heterojunction interface possesses stronger electrical transport ability and is less prone to capture electrons compared with the TiO/MAPbI heterojunction interface. The differential charge density spectrum shows that the density is lower in the trap energy level of SnO/MAPbI, whilst the effect of the charge transfer defect is weaker owing to the trap energy level only existing in SnO. The SnO/MAPbI heterostructure interface is less prone to capture electrons. The greater electron concentration difference is attributed to oxygen vacancy (Vo) in the SnO-like environment, resulting in superior electron transport ability compared with the TiO-like environment.