Stabilization of Perovskite Solar Cells by a Universal Dilution Strategy: The Crystallization Control of Blade-Coating.

Solvent engineering is one of the most effective strategies to control perovskite film quality, which directly affects the performance of perovskite solar cells (PSCs). Here, we introduce volatile acetonitrile (ACN) into the traditional solvent system (i.e., N,N -dimethylformamide and N -methyl-2-pyrrolidone) to dilute the perovskite precursors from 1.43 M to lower concentration (0.6-0.8 M). The dilution strategy can effectively improve the stability of the precursor solution and maintain similar film quality and device performance as those with high solution concentration (1.43 M). Notably, the devices with low-concentration precursors (0.6-0.8 M) show efficiency of 20.85% and improved long-term (>1000 h) storage stability compared to the device with high precursor concentration by blade-coating. Meanwhile, the material cost can be reduced by more than 50% when diluting to 0.6-0.8 M. These results demonstrate a universal dilution method which can provide guidance for the research and development of low-cost and high stability PSCs.