 The two-step coding method of perovskite CH3 and H3PBI3 light absorber on mesoporous TiO2 layer results in higher average power conversion efficiency, 13.9%, compared to the one-step coding method, 7.5%, due to better voltage and fill factor, while coverage, poor filling, and morphology are critical factors affecting photovoltaic performance of mesoporous TiO2-based perovskite solar cells. This article was authored by Jong Hyakim, Huisiin Kim, and Namgyu Park.