High efficiency planar perovskite solar cell by surface disorder removal on mesoporous tin oxide

• Ethanol is introduced to remove the surface disorder of mesoporous SnO 2 . • The charge transport is enhanced at interface and high-quality perovskite film is obtained. • The device after ethanol treatment exhibits a high PCE from 20.70% to 21.62%. • Long term stability of devices with ethanol treatment are promoted, especially for light and thermal duration. Tin oxide (SnO 2 ) is widely used in perovskite solar cells (PSCs) as an electron transport layer (ETL) material. Ethanol usually serves as a solvent of ETL but no one discussed the possible influences caused by ethanol. In this work, the effects of ethanol were investigated systematically. It is clear that ethanol treatment (EtOH-SnO 2 ) can remove surface disorder of mesoporous SnO 2 and thus enhance the conductivity as well. As a result, the champion PCE of 21.62% is obtained in PSC with EtOH-SnO 2 ETL, which is higher than that of control device (20.70%) due to improved film quality. Meanwhile, compared with control PSCs, the stability of the perovskite layer deposited on EtOH-SnO 2 ETL is gradually improved both for the light and thermal stability. Therefore, we make clear that the ethanol treatment can improve the quality of mesoporous SnO 2 and perovskite films for optoelectronic device.