Efficient and Stable 2D@3D/2D Perovskite Solar Cells Based on Dual Optimization of Grain Boundary and Interface

Abstract

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.