Abstract
Perovskite solar cells (PSCs) based on a NiO x hole transport layer (HTL) with an inverted p-i-n configuration have yielded highly efficient and relatively stable devices. Here, we develop a simple electrochemical deposition method for quickly and evenly preparing a mesoporous NiO x film. It is demonstrated that the increasing thickness and decreasing surface roughness of the NiO x film are beneficial for light transmission. The optimal condition for preparing NiO x films is achieved by adjusting the deposition time at a certain applied current density, which exhibits excellent optical transmittance and suitable thickness and band gap, thus reducing optical loss and enhancing hole extraction at the interface between HTL and the perovskite layer and therefore improving photovoltaic performances. The finite-difference time-domain simulation confirms the optimal thickness of the NiO x layer and coincides with our experiment results. An optimal power conversion efficiency (PCE) of 17.77% with an active area of 0.25 cm2 is achieved. The prepared device shows negligible hysteresis, high reproducibility, and high uniformity with a PCE difference of 2% for measuring the different sites from edge to center. This simple fabrication process paves a novel way to the evolution of PSCs based on NiO x and rapid commercialization.