Enriched Fluorescence Emission from WS 2 Monoflake Empowered by Au Nanoexplorers

Gold nanoparticles (Au NPs) are deposited on monolayer 2D tungsten disulfide (WS 2 ) microflake (monoflake) to probe the effects of gold deposition on the physical and chemical properties of the WS 2 transition metal dichalcogenides. It is found that the Au NPs behave like nanoexplorers that map out subtle and hidden chemical heterogeneity within the WS 2 monoflake by way of site‐selective decoration on the WS 2 monoflake. The resultant decorated Au NPs patterns trace the concentric fluorescence pattern found on the WS 2 monoflake. The Au NPs enhance the fluorescence intensity in selected regions within the WS 2 monoflake and even activate fluorescence emission from previously dark regions. Most remarkably, the photoluminescence spectra from WS 2 with Au NPs are sharpened and dominated by neutral excitons. This is in stark contrast to photoluminescence emission from pristine WS 2 monoflake where the spectrum exhibits a multitude of emissions from trions, biexcitons, neutral excitons, and defect‐bounded excitons.