Carbene Functionalization of Monolayer Tungsten Disulfide for Enhanced Quantum Emission

Area of Science:

• Materials Science
• Quantum Photonics
• Nanotechnology

Background:

• Semiconducting two-dimensional (2D) transition metal dichalcogenides (TMDs) are vital for electronic and photonic devices.
• Chemical functionalization customizes TMD properties, but solution-based methods lack control over adlayer uniformity.
• High-performance applications require precise control over adlayer thickness and coverage.

Purpose of the Study:

• To develop a vapor-phase functionalization method for 2D TMDs.
• To investigate the effect of N-heterocyclic carbenes (NHCs) on tungsten disulfide (WS2).
• To enhance the quantum emission properties of WS2 for single-photon applications.

Main Methods:

• Vapor-phase reaction of N-heterocyclic carbenes (NHCs) with monolayer tungsten disulfide (WS2).
• Photoluminescence spectroscopy at cryogenic temperatures.
• Second-order correlation measurements (g(2)) to assess single-photon emission.
• Density functional theory (DFT) calculations and chemical characterization.

Main Results:

• Achieved molecularly smooth, thin, and uniform NHC adlayers on WS2.
• Reduced photoluminescence background by 58%, enabling single-photon emitter detection.
• Observed low second-order correlation values (g(2) = 0.17 ± 0.07).
• DFT calculations indicated dual defect-passivation and doping effects of NHC adlayers.

Conclusions:

• Vapor-phase carbene functionalization is an effective surface modification technique for 2D TMDs.
• This method significantly enhances single-photon emission properties of WS2.
• The approach offers a pathway for tailoring quantum emission in semiconducting 2D materials for quantum technologies.