First-Principles Study of Electronic Properties of SnO 2 /CsPbI 2 Br Interface

More research work has focused on device structure preparation, doping modification, and interface control of CsPbI2Br-based solar cells, whereas less basic theoretical research has been carried out on CsPbI2Br-based perovskite solar cells. It is necessary to find a suitable method to accurately describe the microscopic properties of CsPbI2Br-based perovskite solar cells. Therefore, this paper starts from the interface regulation of all-inorganic perovskite CsPbI2Br to study in detail the local lattice and electronic properties of the light-absorbing layer (CsPbI2Br)/electron transporting layer (SnO2) heterogeneous interface at the atomic and electronic levels by using first-principles calculations based on density functional theory (DFT). The results show that the lattice mismatch at the CsPbI2Br (100)/SnO2 (110) heterogeneous interface is 6.4% while the interface binding energy is −0.79 J/m2, indicating that the interface orientation and bonding modes can exist stably. Density of states (DOS) calculations reveal that the CsPbI2Br (100)/SnO2 (110) interface presents some interface states caused by I 5p and O 2p orbitals near to the Fermi level, which is one of the reasons for the low conversion efficiency of such solar cells.