2D/3D wrapping structure: Applications and challenges in perovskite solar cells

Abstract

Although the efficiency of three-dimensional (3D) perovskite solar cells (PSCs) has exceeded 26%, their commercialization remains hindered by environmental instability. Two-dimensional (2D) perovskites, with excellent hydrophobicity and barrier properties, exhibit enhanced environmental stability; however, their quantum-well structure limits charge transport. By combining the advantages of both, researchers have proposed wrapping 2D materials around the surface of 3D films to form a 2D/3D wrapping structure, which synergistically enhances environmental tolerance without compromising the optoelectronic performance of 3D phase. Focusing on this distinctive 2D/3D wrapping structure, this review systematically presents conventional preparation methods for 2D capping layer; commonly used cations for 2D capping materials, along with cations worthy of exploration and the characteristics of high-performance cations; the excellent physical properties reported for 2D/3D wrapping structures, including defect passivation, energy-level alignment, crystallization optimization, and phase-structure stabilization; current research hotspots concerning 2D/3D wrapping structures, including suppression of ion migration, facilitation of charge-carrier transport, enhancement of oriented growth of 2D components, and applications in tandem solar cells; and future issues requiring attention, including the influence of the 2D material’s n value on the performance of the wrapping structure and physical mismatches induced by 2D cations. This review supports further optimization of 2D/3D wrapping structures, elucidates their physicochemical mechanisms during photovoltaic energy conversion, and provides a foundation for improving the stability and efficiency of PSCs.