Improved Device Performance and Stability of Less Toxic Solvent-Processed Perovskite Solar Cells with Self-Assembled Molecules

Recently, organic–inorganic hybrid perovskite solar cells (PSCs) have attracted extensive research interest. At present, the main solvent commonly used in perovskite precursor solution is N,N-dimethylformamide (DMF), but DMF solvent is highly toxic with high volatility at room temperature, which is not conducive to the large-scale promotion of perovskite solar cells. N-Methyl pyrrolidone (NMP) is considered to be a green solvent with less toxicity, and it can biodegrade with less harm to the human body and the environment, which is conducive to the commercialization and wide-scale adoption of PSCs. However, the harmful chemical reactions and the mismatched energy levels between the perovskite film prepared by using NMP as a single solvent for the perovskite precursor and the NiOx layer limit the photoelectric performance of PSCs. Therefore, we introduced MeO-2PACz to optimize the lower interface of the perovskite film, which resulted in a higher quality perovskite film, thereby improving the photoelectric conversion efficiency (PCE) and stability of the PSCs. As a result, the NiOx/MeO-2 Pacz-based PSCs achieved a champion PCE of 17.69%, which is currently the highest efficiency that can be achieved by NMP-processed perovskite films. In addition, the device maintains above 80% of the initial PCE value after being stored in air at 25 °C with a relative humidity of 20–30% for 600 h.