Generating Narrow Defect Emission in Monolayer Tungsten Disulfide through Chemical Functionalization*

Monolayer transition metal dichalcogenides (TMDs) have valuable excitonic properties for quantum optoelectronic applications, especially as platforms for single photon emission (SPE). Most studies of TMD quantum emission have focused on tungsten diselenide (WSe₂), leveraging intrinsic defects and strain engineering to localize excitons for SPE. While creating quantum emission from WSe₂ is reliable, the properties of that emission are inconsistent. Rather than relying on unpredictable intrinsic defects, this work introduces controlled extrinsic defects to tungsten disulfide (WS₂) using chemical functionalization methods built on those recently used with WSe₂ [1]. By treating the TMD surface with specific molecules, we engineer new defect sites. Specifically, treating unstrained monolayer WS₂ with maleimide molecules results in narrow, localized photoluminescence peaks at cryogenic temperatures. We apply additional chemical treatments to suppress native WS₂ emission to isolate the narrow peaks. These findings demonstrate that innovative methods such as chemical functionalization are powerful tools for enhancing the suitability of TMD defect emission for quantum optoelectronics. 

 

[1] Utama, M.I.B., Zeng, H., et al. “Chemomechanical Modification of Quantum Emission in Monolayer WSe₂.” Nat Comm 14, 2193 (2023).