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As one kind of promising next‐generation photovoltaic devices, perovskite solar cells (PVSCs) have experienced unprecedented rapid growth in device performance over the past few years. However, the practical applications of PVSCs require much improved device long‐term stability and performance, and internal defects and external humidity sensitivity are two key limitation need to be overcome. Here, gadolinium fluoride (GdF3) is added into perovskite precursor as a redox shuttle and growth‐assist; meanwhile, aminobutanol vapor is used for Ostwald ripening in the formation of the perovskite layer. Consequently, a high‐quality perovskite film with large grain size and few grain boundaries is obtained, resulting in the reduction of trap state density and carrier recombination. As a result, a power conversion efficiency of 21.21% is achieved with superior stability and negligible hysteresis.

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The development of perovskite solar cells has been faster than that of other photovoltaic cells, but their practical application is limited by further improvements in their performance and stability. A 3D/ 2D hybrid perovskite, combining the high efficiency of a 3D perovskite and the prominent stability of a 2D perovskite, is very promising. Herein, a strategy is designed by introducing 2-(2-pyridyl)ethylamine (2-PyEA) molecules with 2D structure and N atoms with a lone electron pair into perovskite. As an additive, 2-PyEA promotes the generation of 2D@3D perovskite; as a post-treated modifier, 2-PyEA facilitates the formation of 2D@3D/2D perovskite. The grain boundary and interface thus are dualoptimized in 2D@3D/2D perovskite by 2-PyEA. It is verified that defect density is reduced, residual stress is relieved, gradient energy is generated, charge transfer is improved, and carrier life is extended. Consequently, the dual-optimized PSC achieves a maximum power conversion efficiency of 23.2% with a negligible hysteresis and satisfactory stability, demonstrating a wonderful effect of 2-PyEA in forming efficient and stable PSCs.

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