A facile spray-assisted fabrication of homogenous flat CH3NH3PbI3 films for high performance mesostructure perovskite solar cells

A homogenous coverage of the CH3NH3PbI3 light absorption layer is crucially important for a high-performance metal-organic halide perovskite solar cell (PSC). Herein, we found that a facile spray-assisted process instead of the commonly used dipping process in a two-step spin-coating method can effectively reduce the roughness (of RMS only 16 nm), enhance the coverage of the light absorption layer and eliminate the pinholes in the layer. The experimental results demonstrated that the PSC's average open-circuit voltage (V-oc) has been raised up from 0.823 +/- 0.105 V to 0.940 +/- 0.008 V by the spray-assisted process. It benefits from the low leakage possibility between the hole-transport-material (HTM) and the mesoporous TiO2 layer when a smooth and pinhole-free light absorption layer has successfully formed. Finally the average power conversion efficiencies of the mesostructure PSCs could be promoted by 25% approximately. (C) 2015 Elsevier B.V. All rights reserved.