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

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.