Methylammonium lead halide perovskites have been widely investigated as light absorption materials for efficient solution- processed solar cells due to their superior optoelectronic properties. Nowadays, the certified efficiency of perovskite solar cells (PSCs) has already reached as high as 22%, proving to be a candidate for silicon solar cell and organic photovoltaic owing to the lower cost, higher efficiency, and easier fabrication. Currently, two types of architectures for PSCs have been employed, which depend on the relative positions of the electron and hole transport layers. The inverted (p–i–n) planar device architectures typically employing a MAPbI3–PCBM ([6,6]–phenyl–C61–butyric acid methyl ester) bilayer junction has attracted extensive attention because of their simple fabrication and relatively small hysteresis. The most popular p-type material used in inverted planar device is poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), which, however, is not good for long-term stability due to its high acidity and hygroscopicity even if it can be suitable for flexible solar cell. In comparison with organic hole conductors, p-type inorganic materials are usually chemically stable and cost-effective.

     NiO is a promising hole transporting material for PSCs due to its high hole mobility, good stability and easy processibility. In this work, we employed a new simple solution-processed NiO film as the hole-transporting layer, and fabricated a device with structure FTO/NiO/perovskite/PCBM/Ag. After optimization of thickness and roughness of NiO layer by spin-coating different times precursor, and thickness of perovskite layer by utilizing different concentration chlorobenzene assisted one-step rapid crystallization perovskite, the optimal device fabrication conditions are determined by using photoluminescence spectra, XRD, SEM and other photovoltaic characterizations. A best power conversion efficiency of 14.87% was obtained with a Jsc of 19.42 mA·cm^-2, a Voc of 987.8 mV and a FF of 77.51% and a stable efficiency of 15.1% was catching at maximum power point tracking.The work is under optimizing, and the performance will be further improved.  

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