Spray-coated wide-bandgap perovskite solar cells offer a low-cost, highly scalable, and substrate-adaptive fabrication approach, holding significant promise for applications in perovskite-based tandem solar cells. However, the uncontrollable volatilization process and the randomly distributed nucleation sites lead to increasingly severe surface roughness and defect formation in the perovskite films as the number of spray-coated layers increases. Here, a solid-phase cyanoacetamide compound, N,N-d