Heterogeneous Nucleation and Enhanced Charge Transfer via Amorphous Metal-Organic Frameworks for Efficient and Stable Perovskite Solar Cells

The two-step sequential deposition method is considered a potential way for the large-scale manufacture of perovskite solar cells (PSCs) with high power conversion efficiency and reproducibility. However, the dense lead iodide (PbI₂) film interferes with its full contact with organic solutions, resulting in an inadequate reaction at the interface. Herein, 2 kinds of metal-organic framework (MOF) are introduced, amorphous Ni-MOF-74 (_amNi-MOF-74) and crystalline Zn-MOF-74 (_crZn-MOF-74), into PbI₂ for regulating crystallization. Compared to _crZn-MOF-74, the incorporation of _amNi-MOF-74 exhibited rapid nucleation, resulting in high-quality perovskite films with large grain size, low trap density, and enhanced charge transfer between the perovskite and charge transfer layers. Meanwhile, the content of unstable phase PbI₂ left in perovskite films due to insufficient reaction is also reduced. The _amNi-MOF-74 modified PSCs exhibited a champion power conversion efficiency of 24.17% with good humidity and thermal stability. The unencapsulated device maintains 90% of its initial efficiency after 1000 h storage in dark ambient conditions with ≈30% relative humidity. This strategy provides an effective approach for promoting the crystallization process of perovskite and fabricating efficient and stable PSCs.