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 ‐SnO 2 ) 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 ‐SnO 2 nanoparticles generated by the solution‐processed approach seriously limit the performance of the OSCs with n ‐SnO 2 ETL. InP/ZnS quantum dots (QDs) are employed to passivate the surface defects of n ‐SnO 2 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 ‐SnO 2 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 ‐SnO 2 /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 ‐SnO 2 ETL to develop efficient and stable OSCs.