Passivating Surface Defects of n‐SnO₂ Electron Transporting Layer by InP/ZnS Quantum Dots: Toward Efficient and Stable Organic Solar Cells

Abstract N‐type tin oxide (n‐SnO₂) nanoparticle film has shown great potential as an electron transport layer (ETL) in fabricating highly efficient organic solar cells (OSCs) due to its low‐temperature preparation and high electrical conductivity. However, surface defects on the n‐SnO₂ nanoparticles generated by the solution‐processed approach seriously limit the performance of the OSCs with n‐SnO₂ ETL. InP/ZnS quantum dots (QDs) are employed to passivate the surface defects of n‐SnO₂ ETL, and an inverted OSC using PM6:Y6 as active layer achieves a power conversion efficiency (PCE) of 15.22%, much higher than that of a device based on pure n‐SnO₂ ETL (13.86%). The synergistic enhancement of the device open‐circuit voltage (V_oc) and fill factor (FF) is attributed to the improved morphologies of PM6:Y6 layer on the QDs/ETL, increased charge extraction and collection efficiency, and decreased monomolecular recombination caused by the defect‐trapped charge carriers in the solar cell. Moreover, the inverted device with n‐SnO₂/InP/ZnS QDs ETL show a much higher stability than that of the conventional PEDOT:PSS based one. This work presents a promising QDs passivation strategy on n‐SnO₂ ETL to develop efficient and stable OSCs.