Inverted hole-transporting-layer (HTL) free planar perovskite solar cells are fabricated in ambient conditions. The perovskite layers are prepared via a two-step process on electrodeposited Cu2O particles, and a compact, homogenous, and pin-hole free morphology with extremely large grains are obtained. The high quality of the perovskite films is attributed to that the Cu2O particles can act as the growing sites of crystal nucleus of perovskite films during annealing. The optimized device shows a power conversion efficiency of 9.64%. Such a PCE is one of the highest values among the reported inverted HTL-free perovskite solar cells even it is fabricated in a high humidity condition. (C) 2016 Elsevier B.V. All rights reserved.