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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 dual-optimized 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.
Li et al. (Mon,) studied this question.