Photoinduced carrier transfer dynamics in a monolayer MoS₂/PbS quantum dots heterostructure

Two-dimensional molybdenum disulfide (MoS₂) has been proven to be a candidate in photodetectors, and MoS₂/lead sulfide (PbS) quantum dots (QDs) heterostructure has been used to expand the optical response wavelength of MoS₂. Time-resolved pump-probe transient absorption measurements are performed to clarify the carrier transfer dynamics in the MoS₂/PbS heterostructure. By comparing the carrier dynamics in MoS₂ and MoS₂/PbS under different pump wavelengths, we found that the excited electrons in PbS QDs can transfer rapidly (<100 fs) to MoS₂, inducing its optical response in the near-infrared region, although the pump light energy is lower than the bandgap of MoS₂. Besides, interfacial excitons can be formed in the heterostructure, prolonging the lifetime of the excited carriers, which could be beneficial for the extraction of the carriers in devices.