Decoding Buried Interfaces in Perovskite Solar Cells: Core Issues, Strategic Engineering, and Prospects for High‐Efficiency Stable Devices

Perovskite solar cells (PSCs) have emerged as a frontrunner in photovoltaic technologies, owing to their high performance and low-cost scalability. However, their efficiency remains substantially below the theoretical Shockley-Queisser limit (>30%), and their long-term stability is severely compromised; both are predominantly driven by interface-related issues. Compared to the top interface, buried interfaces are equally important, if not more important, effects on perovskite film quality and device performance. This review comprehensively analyzes challenges at buried interfaces, including defects, terminations, strain, carrier dynamics, and chemical reactions, with special focus on self-assembled monolayer (SAM)-based devices and textured interfaces in perovskite/silicon tandem solar cells. Targeted modification strategies such as defect passivation, strain control, carrier transport modulation, and inhibition of adverse reactions are proposed to mitigate these issues. Finally, research prospects for optimizing buried interfaces are outlined, including advanced in situ characterizations, novel charge transport materials, and innovative interface engineering to enhance PSC performance and stability.