Molecular-Perspective Insights into Top Interface Passivation in Inverted Perovskite Solar Cells

Inverted perovskite solar cells (IPSCs) have emerged as a promising research focus in photovoltaics due to their outstanding optoelectronic properties. However, the further development of IPSCs on efficiency and stability is still limited by the rich defects of perovskites, especially at the top interface of the film. To address the challenge of defects, researchers have demonstrated various studies to suppress the defect effects and enhance the device performance of IPSCs. This review systematically examines the chemical origins of defects at the perovskite top interface and summarizes recent progress in interfacial passivation strategies. Specifically, first various top interface defects and the mechanisms of them influence the perovskite film and device performance are analyzed. Second, this review critically evaluates the efficacy of state-of-the-art passivation strategies, including organic amine halides for 2D/3D heterostructure engineering and tailored molecular structures, Lewis acid and Lewis base passivation, multifunctional group synergistic passivation, and other passivation strategies. The evaluation criteria integrate molecular-level design rationality, interface engineering, and in situ characterization strategies. Finally, this review concludes and establishes fundamental design principles for high-stability passivation materials and critically evaluates their scalability potential, aiming to provide theoretical guidance for the development of highly efficient and stable IPSCs.