Highly-efficient perovskite solar cells based on controllable oxygen defects in tin oxide electron transport layers

Defects regulation of metal oxide electron transport layers (ETLs) such as SnO2 is an effective strategy for improving the power conversion efficiency (PCE). However, it is difficult to control the surface defects of SnO2 using low boiling point solvents, thereby limiting the performance of the perovskite solar cells (PSCs). For this, we prepared high-quality SnO2 films by a low-temperature solution method, and found that solvent had an obvious influence on the energy level and oxygen vacancy within SnO2. The SnO2 electron transport layer was prepared by isopropanol (I–SnO2) dimethoxyethanol (D-SnO2), respectively. Comparing with I–SnO2, D-SnO2 shows excellent photoelectric properties. The perovskite cells based on D-SnO2 exhibited the optimal performance, and the efficiency increased to 20.35% from 18.63% of the device based on I–SnO2.