Effects of Acetone Vapor on the Exciton Band Photoluminescence Emission from Single- and Few-Layer WS2 on Template-Stripped Gold.

Two-dimensional (2D) materials are being used widely for chemical sensing applications due to their large surface-to-volume ratio and photoluminescence (PL) emission and emission exciton band tunability. To better understand how the analyte affects the PL response for a model 2D platform, we used atomic force microscopy (AFM) and co-localized photoluminescence (PL) and Raman mapping to characterize tungsten disulfide (WS2) flakes on template-stripped gold (TSG) under acetone challenge. We determined the PL-based response from single- and few-layer WS2 arises from three excitons (neutral, A0; biexciton, AA; and the trion, A-). The A0 exciton PL emission is the most strongly quenched by acetone whereas the A- PL emission exhibits an enhancement. We find the PL behavior is also WS2 layer number dependent.