Energetically favored formation of SnO2 nanocrystals as electron transfer layer in perovskite solar cells with high efficiency exceeding 19%

Low temperature fabrication of SnO2 electron transfer layer (ETL) below 80 °C is realized by synthesis of SnO2 nanocrystals through an energetically favorable wet chemical route. The SnO2-ETLs with high conductivity and transmittance, appropriate band edge and wide band gap endow planar PSCs with high efficiencies and superb UV resistance.178