Observation of Charge Transfer in Heterostructures Composed of MoSe₂ Quantum Dots and a Monolayer of MoS₂ or WSe₂

Monolayer transition metal dichalcogenides (TMDs) are atomically thin semiconductor films that are ideal platforms for the study and engineering of quantum heterostructures for optoelectronic applications. We present a simple method for the fabrication of TMD heterostructures containing MoSe₂ quantum dots (QDs) and a MoS₂ or WSe₂ monolayer. The strong modification of photoluminescence and Raman spectra that includes the quenching of MoSe₂ QDs and the varied spectral weights of trions for the MoS₂ and WSe₂ monolayers were observed, suggesting the charge transfer occurring in these TMD heterostructures. Such optically active heterostructures, which can be conveniently fabricated by dispersing TMD QDs onto TMD monolayers, are likely to have various nanophotonic applications because of their versatile and controllable properties