Energy Transfer Dynamics between Carbon Quantum Dots and Molybdenum Disulfide Revealed by Transient Absorption Spectroscopy

Zero-dimensional environmentally friendly carbon quantum dots (CQDs) combined with two-dimensional materials have a wide range of applications in optoelectronic devices. We combined steady-state and transient absorption spectroscopies to study the energy transfer dynamics between CQDs and molybdenum disulfide (MoS₂). Transient absorption plots showed photoinduced absorption and stimulated emission features, which involved the intrinsic and defect states of CQDs. Adding MoS₂ to CQDs solution, the lowest unoccupied molecular orbital of CQDs transferred energy to MoS₂, which quenched the intrinsic emission at 390 nm. With addition of MoS₂, CQD-MoS₂ composites quenched defect emission at 490 nm and upward absorption, which originated from another energy transfer from the defect state. Two energy transfer paths between CQDs and MoS₂ were efficiently manipulated by changing the concentration of MoS₂, which laid a foundation for improving device performance.