Stable one dimensional (1D)/three dimensional (3D) perovskite solar cell with an efficiency exceeding 23%

Abstract The interface properties of organic–inorganic mixed halide perovskite solar cells play a significant role in their photovoltaic performance. Defect states at the interface can decrease the power conversion efficiency through defect‐assisted charge recombination and degrade the long‐term stability. Low‐dimensional perovskites exhibit excellent stabilities. They can be combined with three dimensional (3D) perovskites to utilize their advantages for fabrication of high‐performance devices. In this study, we successfully construct a robust interface for perovskite films through mixed‐dimensional engineering. After the introduction of a one dimensional (1D)‐structured capping layer on the 3D perovskite through post‐treatment, the number of defect states in the perovskite film is significantly decreased, while the lifetime of the photocarriers is increased. In addition, the 1D capping layer can serve as a diffusion barrier to reduce the ion migration and protect the vulnerable 3D perovskite against moisture. Perovskite solar cells based on stacked 1D/3D structures exhibit a power conversion efficiency of 23.3% and maintain 80% of the initial efficiency after storage for over 800 h under ambient conditions with a humidity of 50%. Their performances are superior to those of the 3D devices. This study provides a simple approach to simultaneously enhance the efficiency and stability of perovskite solar cells and may guide the development of other solar cells. image