Amino-acid-type alkylamine additive for high-performance wide-bandgap perovskite solar cells

•An amino-acid-type alkylamine additive for wide-bandgap perovskite solar cells.•The optimized perovskite film exhibit enhanced crystallinity and orientation.•The anti-site defects and halide vacancies were effectively passivated.•The power conversion efficiency was improved to 21.13% with improved stability.