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.

Perovskite solar cells with vanadic oxide doping achieve a power conversion efficiency of 20.5%.

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The 2D/3D composite structure possesses both the excellent stability of 2D perovskite and the excellent performance of 3D perovskite, which recently have attracted special attention. Different from the popular isopropanol, a novel additive solvent—polypropylene glycol bis (2‐aminopropyl ether) (A‐PPG) is introduced here to dissolve excess PbI2 and perovskite, and then reconstruct and in situ form the quasi‐2D perovskite layer on 3D perovskite bulk. The lone electron pairs of the ether‐oxygen and amino in A‐PPG can form coordination bonds with Pb2+. The introduction of A‐PPG tunes the energy array of functional layers, passivates defects, and mitigates carrier nonradiative recombination. Consequently, the 2D/3D perovskite device exhibits a championship efficiency of 22.24% with a distinguished open‐circuit voltage of 1.21 V (the thermodynamic limit of 1.30 V). Moreover, the 2D/3D device still maintains 90% of the original efficiency in the ambient atmosphere with a relative humidity of 30 ± 10% after 50 days.

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