Suppressing Non‐Radiative Relaxation through Single‐Atom Metal Modification for Enhanced Fluorescence Efficiency in Molybdenum Disulfide Quantum Dots

To enhance the fluorescence efficiency of semiconductor nanocrystal quantum dots (QDs), strategies via enhancing photo-absorption and eliminating non-radiative relaxation have been proposed. In this study, we demonstrate that fluorescence efficiency of molybdenum disulfide quantum dots (MoS2 QDs) can be enhanced by single-atom metal (Au, Ag, Pt, Cu) modification. Four-fold enhancement of the fluorescence emission of MoS2 QDs is observed with single-atom Au modification. The underlying mechanism is ascribed to the passivation of non-radiative surface states owing to the new defect energy level of Au in the forbidden band that can trap excess electrons in n-type MoS2 , increasing the recombination probability of conduction band electrons with valence band holes of MoS2 . Our results open an avenue for enhancing the fluorescence efficiency of QDs via the modification of atomically dispersed metals, and extend their scopes and potentials in a fundamental way for economic efficiency and stability of single-atom metals.