Binary Additive Engineering Enables Efficient Perovskite Solar Cells via Spray-Coating in Air

Spray-coating as a high throughput and low-cost deposition process endows perovskite solar cell (PSC) devices the possibility of large-scale production, while the low device efficiency due to poor and uncontrolled film quality impedes the commercialization process of PSCs. Herein, we demonstrate a binary additive engineering strategy to achieve a device efficiency of 18.2% with minor hysteresis by spray-coating the (FAPbI₃)_x(MAPbBr₃)_1–x hybrid perovskite in air. The spray-coated perovskite films have a hierarchical structure that is composed of large grains of over 100 μm and small grains of around 400 nm. The incorporation of L-α-phosphatidylcholine additive in the perovskite precursor improves crystallinity, narrows grain boundaries between large grains, and passivates FA⁺/MA⁺ vacancies, consequently increasing light absorption and reducing trap-assisted charge recombination to improve efficiency. The addition of KI additive increases the large-grain size and passivates defects, thereby reducing hysteresis as well as further enhancing efficiency. This work introduces a facile binary additive approach to fabricate high efficiency, one-step spray-coated PSCs in ambient conditions.