Fig. 4

Field-effect control of bilayer WSe₂ photoluminescence. a Normalized photoluminescence (brown) of a bilayer WSe₂ encapsulated in hexagonal boron nitride and tuned toward charge neutrality with positive gate voltages. Best fit to the spectrum (red) was obtained with the same set of excitons energies as in Fig. 1c and an overall redshift of 2 meV. b Evolution of the photoluminescence with gate voltage from −30 to 30 V. Note the cross-over to the charged regime below −20 V signified by a simultaneous redshift of 22 meV for all peaks as indicated by the red arrows below the dashed line