Optimizing the Performance of Sputtered-NiOx-Based Perovskite Solar Cells via Regulating the PbI2 Concentration

Nickel oxide (NiOx) prepared by sputtering is a promising hole transport material for inverted planar perovskite solar cells (PSCs) because of its wide bandgap, deep valance band edge, excellent optical transmittance, and low cost. However, the interface reaction between sputtered-NiOx and perovskite layer leads to the formation of lead iodine on perovskite surface, which limits the efficiency and stability of the device. Herein, we report a facile approach to improve the performance of the sputtered-NiOx-based PSCs via precise control the concentration of PbI2 in precursor solution. It is demonstrated that the concentration of PbI2 has a significant effect on the microstructure and photoelectric properties of the perovskite layer deposited on sputtered-NiOx. When the PbI2 concentration is 2% less than the stoichiometric perovskite, the efficiency of the optimized device is improved to 15.64%, and the device stability under unencapsulated atmospheric conditions is also significantly improved. In the optimized sample, a small amount of residual PbI2 still exists in perovskite films, which is proved beneficial for passivating grain boundary defects and enhancing the performance of the PSCs. This work provides a feasible way for enhancing the performance of sputtered-NiOx-based PSCs as well suggest a probability for reducing the consumption of PbI2.