LAUSR

Abstract Interface engineering has been widely applied to perovskite solar cells (PSCs) for solving the problems caused by high density of parasitic traps and the defects that exist at grain boundaries and surfaces. Various inorganic metal oxides play roles in PSCs, helping to achieve higher efficiency and better long-term stability. In this work, two-phase hydrothermal method is used for CoFe2O4 nanocrystals (NCs) synthesis and the obtained NCs were used to modify the surface between perovskite (PVK) and hole transport layer (HTL). Results show that CoFe2O4 modified devices have enhanced hole extraction, reduced trap density, and hydrophobic ligand connected to CoFe2O4 NCs provide better moisture resistance to PVK layer. Devices with CoFe2O4 layer exhibit a best PCE of 19.65% with improved open circuit voltage (VOC), fill factor (FF) and reproducibility. At steady-state, CoFe2O4 modified devices show a current density of 20.16 mA/cm2 and PCE of 18.97%.