LiF-Modified SnO_2 Electron Transport Layer Improves the Performance of Carbon-Based All-Inorganic CsPbIBr_2 Perovskite Solar Cells

摘要

SnO_2 has gained wide attention because of its low synthesis temperature (approximately 150 ℃), high electron mobility, and low manufacturing cost. However, the lattice mismatch at the SnO_2/CsPbIBr_2 interface and the oxygen vacancy leads to nonradiative recombination. Therefore, the key to improving the performance is to remove the defects between the SnO_2 and the CsPbIBr_2. In this paper, the first-principles calculation and experimental results show that the doping of LiF can enhance the conductivity of SnO_2 films and improve the energy band alignment at the SnO_2/CsPbIBr_2 interface, which enhances interfacial carrier transport. Furthermore, the doping of LiF can adjust the lattice constants of the SnO_2 films and decrease the lattice mismatch between SnO_2 and CsPbIBr_2. The results showed that the LiF-modified SnO_2 used at the optimum concentration had the best power conversion efficiency (PCE) based on SnO_2:LiF/perovskite of 6.58%, which is nearly 34.83% higher than that of the pure CsPbIBr_2 perovskite solar cells (PSCs). This work provides an insightful strategy to improve the stability and efficiency of carbon-based all-inorganic CsPbIBr_2 PSCs.