LiF-Modified SnO2 Electron Transport Layer Improves the Performance of Carbon-Based All-Inorganic CsPbIBr2 Perovskite Solar Cells

SnO2 has gained wide attention because of its low synthesis temperature (approximately 150 °C), high electron mobility, and low manufacturing cost. However, the lattice mismatch at the SnO2/CsPbIBr2 interface and the oxygen vacancy leads to nonradiative recombination. Therefore, the key to improving the performance is to remove the defects between the SnO2 and the CsPbIBr2. In this paper, the first-principles calculation and experimental results show that the doping of LiF can enhance the conductivity of SnO2 films and improve the energy band alignment at the SnO2/CsPbIBr2 interface, which enhances interfacial carrier transport. Furthermore, the doping of LiF can adjust the lattice constants of the SnO2 films and decrease the lattice mismatch between SnO2 and CsPbIBr2. The results showed that the LiF-modified SnO2 used at the optimum concentration had the best power conversion efficiency (PCE) based on SnO2:LiF/perovskite of 6.58%, which is nearly 34.83% higher than that of the pure CsPbIBr2 perovskite solar cells (PSCs). This work provides an insightful strategy to improve the stability and efficiency of carbon-based all-inorganic CsPbIBr2 PSCs.