Thermal evaporated CuI film thickness-dependent performance of perovskite solar cells

CuI, as a promising hole transport material, possesses high hole mobility and is compatible with perovskite materials about band structure. Herein, CuI hole transport films are first fabricated by vacuum thermal evaporation procedure for n-i-p perovskite solar cell. The results show that vacuum thermal evaporated CuI films have no obvious influence on perovskite underlayer and 200 nm thick CuI film has the best carrier extraction ability. To further improve the stability of the device, reduced graphene oxides are introduced to avoid the accelerated attenuation caused by the reaction of CuI with Au. Finally, the power conversion efficiency of the dual-modified device improves to 8.69%, with the short circuit current density of 18.86 mA cm−2, the open circuit voltage of 0.832 V and the filling factor of 0.550. The work demonstrates a potential application of vacuum thermal evaporated CuI films in organic-inorganic hybrid perovskite solar cells.