Fig. 4: Photoluminescence (PL) spectra of M3-Tf (M3=Li and Na) and Li-OAc treated MoS2 and WS2 monolayers.

Representative PL spectra for a Li-Tf-treated monolayer MoS2, b pristine and Li-Tf-treated monolayer WS2, c pristine and Na-Tf-treated monolayer WS2, and d pristine and Li-OAc-treated monolayer WS2. The decomposed Lorentzian peak fittings are presented in dashed lines and the cumulative Lorentzian peak fittings are presented in solid lines. Each PL peak position value is stated in the spectra.