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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. [ABSTRACT FROM AUTHOR]

In the past few years, the renormalized excitonic model (REM) approach was developed as an efficient low-scaling ab initio excited state method, which assumes the low-lying excited states of the whole system are a linear combination of various single monomer excitations and utilizes the effective Hamiltonian theory to derive their couplings. In this work, we further extend the REM calculations for the evaluations of first-order molecular properties (e.g. charge population and transition dipole moment) of delocalized ionic or excited states in molecular aggregates, through generalizing the effective Hamiltonian theory to effective operator representation. Results from the test calculations for four different kinds of one dimensional (1D) molecular aggregates (ammonia, formaldehyde, ethylene and pyrrole) indicate that our new scheme can efficiently describe not only the energies but also wavefunction properties of the low-lying delocalized electronic states in large systems. [ABSTRACT FROM AUTHOR]