(Top) Net ion density i+(x, z) − i−(x, z) on the ionic liquid for a Vgs = −2 V (Vref ~ −1.46 V), b Vref = 0.2 V (Vref ~ 0.19 V), and c Vgs = 2 V (Vref ~ 1.38 V). The drain-source voltage is fixed to Vds = 0.2 V. (Bottom) Band profile of WSe2 and the metal. The dotted lines indicate the bottom of the conduction band, Ec (blue), and the top of the valence band, Ev (red). The solid lines denote the quasi-Fermi energy. See Table 1 for the other parameters.