Tunable Photoluminescence in WS₂/WO₃ Monolayer/Nanoparticles Hybrid Structure

Photoluminescence (PL) of WS₂ monolayer has attracted attention triggered by potential optoelectronic and photoelectric applications due to the largest direct band gap in WS₂ monolayer among transition metal dichalcogenides. The PL of WS₂ monolayer is dominated by charged excitons (trions) and bound excitons, which suppress the luminescence of free excitons. Herein, we report a one-step growth of a nanosheet/nanoparticles hybrid structure to reduce the emission of bound excitons and trions in WS₂ monolayer by surface passivation with WO₃ nanoparticles. Peak positions of the PL spectra in WS₂ monolayers depend on the density of WO₃ nanoparticles on their surface. With increasing density of WO₃ nanoparticles, the PL of WS₂ monolayers experiences the transition from bound excitons and charged excitons (trions) to neutral excitons. These results suggest that the engineering of PL of WS₂ monolayers may be realized by surface passivation using nanoparticles of wide band gap semiconductors.