Eco-friendly Solvent Engineered CsPbI 2.77 Br 0.23 Ink for Large-Area And Scalable High Performance Perovskite Solar Cells.

The performance of large-area perovskite solar cells has been assessed for typical compositions, such as methylammonium lead iodide (MAPbI 3 ), using a blade coater, slot-die coater, solution shearing, ink-jet printing, and thermal evaporation. However, the fabrication of large-area all-inorganic perovskite films is not well developed. This study developed, for the first time, an eco-friendly solvent engineered all-inorganic perovskite ink of dimethyl sulfoxide as a main solvent with the addition of acetonitrile, 2-methoxyethanol, or a mixture of acetonitrile and 2-methoxyethanol to fabricate large-area CsPbI 2.77 Br 0.23 films with slot-die coater at low temperatures (40-50°C). We thoroughly examined the perovskite phase, morphology, defect density, and optoelectrical properties of new inks prepared with different solvent ratios and correlated them with their respective colloidal size distribution and solar cell performance. The optimized slot-die-coated CsPbI 2.77 Br 0.23 perovskite film, which was prepared from the eco-friendly binary solvents dimethyl sulfoxide:acetonitrile (0.8:0.2 v/v), demonstrated an impressive power conversion efficiency of 19.05%. Moreover, the device maintained ca. 91% of its original power conversion efficiency after one month at 20% relative humidity in the dark. We believe that this study will accelerate the reliable manufacturing of perovskite devices. This article is protected by copyright. All rights reserved.