Cu-based quaternary chalcogenide Cu2BaSnS4 thin films acting as hole transport layers in inverted perovskite CH3NH3PbI3 solar cells

Efforts toward developing efficient and stable inorganic hole transport materials for inverted perovskite CH3NH3PbI3 solar cells are underway. Herein, a wide bandgap p-type quaternary chalcogenide Cu2BaSnS4 semiconductor is demonstrated as a promising hole transport material in inverted perovskite CH3NH3PbI3 thin-film solar cells owing to its satisfactory chemical stability, high carrier mobility ( similar to 10 cm2 V-1 s-1), and suitable band alignment with CH3NH3PbI3. Our inverted solar cell based on a 100 nm thick Cu2BaSnS4 hole transport layer achieves a best PCE of similar to 10% with a low degree of current-voltage scan hysteresis.