Layer-Dependence of Charge Transfer Kinetics in Hybrids of 2D MoS₂ and PbS/CdS Quantum Dots

Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have attracted tremendous attention owing to their unique optical and physical properties. However, weak photon absorption due to their atomically thin thickness prohibits their spectral sensitivity. Here, 2D-MoS₂ with different layers are combined with core/shell PbS/CdS quantum dots (QDs) to produce hybrids with improved photoresponsivity by interfacial charge transfer. The charge transfer kinetics in the hybrids of MoS₂ and PbS/CdS QDs has been revealed by time-resolved photoluminescence (PL) microscopy, showing that the charge transfer rate increases with the layer of MoS₂ increased due to the increased driving force in between conduction band edge of MoS₂ and QDs. We have evaluated the results with the theoretical model of Marcus theory, which is in good agreement with our observation. Understanding the interfacial charge transfer kinetics between QDs and 2D materials is crucial and useful for improving photon-to-current conversion efficiency in next-generation optoelectronics.