Structures and Electronic Properties of Different CH₃NH₃PbI₃/TiO₂ Interface: A First-Principles Study

Methylammonium lead iodide perovskite, CH₃NH₃PbI₃, has attracted particular attention due to its fast increase in efficiency in dye sensitization TiO₂ solid-state solar cells. We performed first-principles calculations to investigate several different types of CH₃NH₃PbI₃/TiO₂ interfaces. The interfacial structures between the different terminated CH₃NH₃PbI₃ and phase TiO₂ are thoroughly explored, and the calculated results suggest that the interfacial Pb atoms play important roles in the structure stability and electronic properties. A charge transfer from Pb atoms to the O atoms of TiO₂ lead to the band edge alignment of Pb-p above Ti-d about 0.4 eV, suggesting a better carries separation. On the other hand, for TiO₂, rutile (001) is the better candidate due to the better lattice and atoms arrangement match with CH₃NH₃PbI₃.