Hidden but Not Forgotten: Unraveling and Engineering the Buried Interface of Inverted Perovskite Solar Cells

Inverted perovskite solar cells (IPSCs) have achieved significant advancement in photovoltaics contributed by their outstanding optoelectronic properties, showing great potential for industrialization and commercialization. Nevertheless, the efficiency and stability of devices are still largely limited by multiple challenges existing in the buried interface of IPSCs. In recent years, researchers have carried out in‐depth investigations and proposed various innovative strategies to address these issues. This review focuses on the most recent progress of IPSCs and systematically probes into the importance and mechanisms governing the buried interface by analyzing challenges associated with interface defects, energy‐level mismatch, chemical stability, and morphological uniformity. It comprehensively reviews the advancements in diverse buried‐interface strategies from the molecular perspective, including organic materials (organic small molecules and polymers), inorganic salts, and low‐dimensional materials (2D layer or 2D/3D heterojunctions, 1D materials, and 0D materials). Furthermore, advanced characterization techniques for the buried interface are summarized focusing on their ability to analyze morphological structure, chemical and electronic states, and carrier dynamics. Finally, we make a conclusion and outline potential challenges and future directions. This review aims to provide a comprehensive theoretical references and guidance for the development of highly efficient and stable IPSCs.