A Cu3PS4 nanoparticle hole selective layer for efficient inverted perovskite solar cells

Cu3PS4 nanoparticles are used as a new inorganic hole selective layer (HSL) to fabricate efficient perovskite thin-film solar cells in the inverted device configuration. Compared with other HSL materials used in efficient perovskite solar cells, Cu3PS4 has the smallest effective mass for holes. Additionally, Cu3PS4 has a valence band energy level of -5.05 eV, which is suitable for effectively extracting holes generated in perovskite absorbers. These reveal intrinsic properties of Cu3PS4 that make it an excellent HSL material for perovskite solar cells. We further find that a Cu3PS4 nanoparticle HSL promotes grain growth of perovskite thin films, which benefits device performance. Our perovskite solar cells using a Cu3PS4 nanoparticle HSL achieve a maximum power conversion efficiency of 18.17% with small hysteresis and a high fill factor of 81.6%, which is significantly better than the performance of the best control device using the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) HSL.