Sarcosine-Mediated Interface Regulation of SnO2 Electron Transport Layer toward High-Performance and Durable MAPbI3 Perovskite Solar Cells

Abstract Driven by exceptional light-to-electricity conversion performance alongside inexpensive solution-phase manufacturing, metal halide perovskite solar cells (PSCs) have emerged as a major focus of next-generation photovoltaic research. Nevertheless, further performance enhancements remain constrained by high defect densities at the electron transport layer (ETL) interface, suboptimal band alignment, and pronounced nonradiative carrier recombination. Herein, a direct incorporation strategy was developed by introducing sarcosine (Sar) into the SnO2 colloidal precursor to regulate the surface properties and chemical environment of the SnO2 electron transport layer, which is associated with improved MAPbI3 perovskite film formation. Spectroscopic characterizations indicate that chemical coordination between the amine/carboxylic moieties of Sar and unsaturated Sn centers at the SnO2 boundary contributes to interfacial defect passivation alongside a favorable energy band alignment. Simultaneously, the boosted surface hydrophilicity promotes uniform precursor coverage and regulates grain nucleation, ultimately yielding perovskite thin films with elevated crystalline order and minimized defect density. Consequently, optoelectronic analyses reveal accelerated interfacial charge transfer and suppressed nonradiative recombination pathways, contributing to reduced hysteresis and significantly improved photovoltaic performance. A champion power conversion efficiency (PCE) of 21.33% is achieved, compared with 18.72% for the control device. In addition, the Sar-modified solar cells exhibit superior operational robustness under continuous light exposure alongside prolonged shelf life stability in unencapsulated ambient air. Overall, this study presents a straightforward yet potent interface modification approach for constructing high-performance, durable MAPbI3 perovskite photovoltaics.