Healing the buried interface with versatile glutamic acid for efficient and stable SnO2-based perovskite solar cells

Effectively suppressing defects at the SnO2/perovskite (PVK) interface is critical for high-performance perovskite solar cells (PSCs). Here, we introduce glutamic acid (Glu) into SnO2, achieving synergistic regulation of the SnO2/PVK interface properties. The introduction of Glu not only significantly suppresses SnO2 agglomeration but also, due to the presence of the dual carbonyl group in the molecule, effectively coordinates with Sn4+ and Pb2+, passivating the defects on both SnO2 and PVK layers. Correspondingly, the density functional theory calculation results indicate that when the amino group in Glu coordinates with Sn4+, the coordination interaction between the terminal carbonyl group (C1=O) and Sn4+ is further enhanced. Therefore, the SnO2–Glu-based PSC achieves a champion power conversion efficiency of 24.35% (0.06 cm2) and 18.50% in the mini-module (15 cm2). The unencapsulated device maintains >92% of its initial efficiency after continuous operation for 1000 h under air. This study reveals the mechanism by which Glu synergistically regulates the multi-interface property, thus providing an effective approach for achieving efficient SnO2-based PSCs.