Gourmet powder functionalization of SnO2 for high-performance perovskite solar cells made in air

•Gourmet powder is used to simultaneously improve the quality of perovskite film and ETL.•The electric dipole effect and crosslinking of MSG can optimize the ETL/perovskite interface.•Reduced defects and effective interfacial charge transfer are achieved.•A power conversion efficiency of 17.71% is obtained with negligible J-V hysteresis in air. In spite of great advances in low-cost fabrication of air-processed perovskite solar cells (PSCs), there are still many opportunities to further improve device performance. Herein, we show that, by introducing monosodium glutamate (MSG) with carboxyl group, amino group, and Na+ cationic, known as gourmet powder, it is likely to simultaneously enhance the quality of perovskite film and electron transport layer, and interfacial charge extraction. As a multifunctional modify agent, the electric dipole effect and strong crosslinking of MSG can effectively reduce defects, accelerate interfacial charge transfer, alleviate hysteresis, and greatly improve performance of air-processed PSCs. Due to these unique characteristics of MSG, the champion power conversion efficiency (PCE) of 17.71% with negligible hysteresis has been achieved based on the structure of FTO/MSG-SnO2/FA0.5MA0.5PbI3/Spiro-OMeTAD/Au. Moreover, the unencapsulated device exhibits remarkable long-term stability, preserving over 91% of its initial PCE after storage in air for 1320 h. Our work provides a green and promising functionalization method for high-performance air-processed PSCs. [Display omitted]