Charge Transfer Dynamics of Core–Shell Quantum Dots and MoS₂ Nanocomposites Using Transient Absorption Spectroscopy

Photoluminescence (PL) quenching mechanisms and charge transfer dynamics of CdTe/CdS quantum dots (QDs) and molybdenum disulfide (MoS 2 ) nanocomposites were explored by using steady-state and transient absorption spectra. The PL intensity of QDs can be quenched by up to 97% at 0.35 mg/mL MoS 2 . In the presence of MoS 2, the ground state bleaching feature of MoS 2 appeared in the transient absorption spectrum of CdTe/CdS–MoS 2 nanocomposites. This is attributed to the electrons of QDs being injected into the band edge of MoS 2 . With increasing MoS 2, there was a red-shifted ground state bleaching, indicating that more band edge electrons lead to a redistribution of the electric field of MoS 2, and the energy level of MoS 2 is decreased. The larger space charge separation of electrons and holes in the nanocomposites would slow down charge recombination, bringing about a slower stimulated emission feature. By adjusting the MoS 2 concentration, we can modulate the charge-transfer dynamics, which may open up new opportunities for the design of optoelectronic devices.