This article reviews internal encapsulation technologies for perovskite solar cells (PSCs) and systematically discusses the core mechanisms of different kinds of internal encapsulation materials in defect passivation and ion migration suppression, thus contributing to improved efficiency and stability of PSCs.

Perovskite solar cells (PSCs), with high power conversion efficiencies, low-cost solution processability, and flexible wearable potential, are promising candidates for the next generation of photovoltaic technology. However, the inherent instability of PSCs caused by different factors seriously hinders their commercialization process. Among various stability improvement strategies, internal encapsulation has emerged as a promising candidate to supplement the limitation of traditional external encapsulation, which can enhance the stability of perovskite materials by introducing macrocyclic chelators, crosslinking molecules, and functional polymers to achieve crystal defect passivation and inhibit ion migration. This review systematically outlines the core mechanism of internal encapsulation technology, discusses the material design, cross-device layer design principles, and application effects in detail. Moreover, the current challenges and prospects of internal encapsulation for PSCs have been discussed.