 The study investigates the impact of micro and nanoscale interface morphology on perovskite crystal formation and device performance, revealing that surface treatments of compact TiO2 can enhance photocondersion efficiency and reduce IV hysteresis, suggesting the importance of underlayer surface morphology in perovskite crystallization. This article was authored by Simi Tokahoshi, Satoshi Uchida, Biancarage V. V. Jayawira, and others.