Stress and Defect Effects on Electron Transport Properties at SnO(2)/Perovskite Interfaces: A First-Principles Insight

[Image: see text] The structural and electronic properties of interfaces play an important role in the stability and functionality of solar cell devices. Experiments indicate that the SnO(2)/perovskite interfaces always show superior electron transport efficiency and high structural stability even though there exists a larger lattice mismatch. Aiming at solving the puzzles, we have performed density-functional theory calculations to investigate the electronic characteristics of the SnO(2)/perovskite interfaces with various stresses and defects. The results prove that the PbI(2)/SnO(2) interfaces have better structural stability and superior characteristics for the electron transport. The tensile stress could move the conduction band minimum (CBM) of CH(3)NH(3)PbI(3) upward, while the compressive stress could move the CBM of SnO(2) downward. By taking into account the stress effect, the CBM offset is 0.07 eV at the PbI(2)/SnO(2) interface and 0.28 eV at the MAI/SnO(2) interface. Moreover, our calculations classify V(I) and I(i) at the PbI(2)/SnO(2) interface and Sn–I, I(i) and Sn(i) at the MAI/SnO(2) interface as harmful defects. The I(i) defects are the most easily formed harmful defects and should be avoided at both interfaces. The calculated results are in agreement with the available experimental observations. The present work provides a theoretical basis for improving the stability and photovoltaic performance of the perovskite solar cells.