The enhanced electric field within a photovoltaic device can drain electrons to the interface of the electrontransporting layer and sensitizer, thereby accelerating charge collection efficiency, reducing the recombination process, and, overall, resulting in solar-to-electric power conversion efficiency increment. Introduction of islands like p−n junction centers to the mesoporous-TiO 2 texture could be an ideal strategy to improve stability and power conversion efficiency of perovskite solar cells. In this work, novel heterostructures of nanosized cobalt-chromium layered double hydroxide and TiO 2 nanoparticles, with a nominal composition, were fabricated and utilized as perovskite underlayer film precursors. The champion device shows the highest power conversion efficiency with an improvement of 17.14%, compared to the 100% TiO 2 paste composition. The offered interfacial distance between n-type TiO 2 nanoparticles and the perovskite light harvester in p−n junction areas prevents direct contact between TiO 2 and perovskite and, consequently, hinders photocatalytically caused perovskite degradation. Daily power conversion efficiency measurement indicates that the unencapsulated champion devicewhich is kept in darkness in ambient airmaintains 92% of the initial efficiency after 25 days.