Inverted perovskite solar cells offer strong potential for scalable, low-cost solar power, but a hidden interface inside the device has limited their performance and durability. Researchers have now introduced crystal-solvate nanoseeds that guide crystal growth and release solvent in a controlled way during heating, improving film quality at this buried layer. The result is smoother, denser material with better electronic properties and stability. A large mini-module achieved 23.15% efficiency with minimal scaling losses.