Effects of annealing temperature of tin oxide electron selective layers on the performance of perovskite solar cells

Efficient lead halide perovskite solar cells have been realized using SnO 2 as electron selective layers (ESLs). Here, we report on the effects of the annealing temperature of solution-processed SnO 2 ESLs on the performance of perovskite solar cells. We find that the cells using low-temperature annealed SnO 2 (LT-SnO 2 ) ESLs outperform the cells using high-temperature annealed SnO 2 (HT-SnO 2 ) ESLs, exhibiting higher open circuit voltages and fill factors. Structural, electrical, optical, and electrochemical characterizations reveal the origin of the performance differences: LT-SnO 2 produces better film coverage, wider band gap, and lower electron density than that of HT-SnO 2 . The confluence of these properties results in more effective transportation of electrons and blocking of holes, leading to lower interface recombination. Therefore, LT-SnO 2 ESLs are preferred for manufacturing perovskite solar cells on flexible substrates.