Fig. 3

a (i) Excitonic transistor designed for engineering the electrostatic potential to control exciton diffusion. Calculated energy variation for the excitons in ON state (free diffusion, ii) and OFF state (potential barrier, iii). Emission images corresponding ON state (free diffusion, iv) and OFF state (potential barrier, v) of the excitonic transistor. Color scale indicated normalized PL intensity. b (i) Control of exciton concentration using an excitonic transistor with h-BN spacer. (ii) Stark shift as a function of applied vertical electric field (\({\mathop {\textit{E}}\limits ^{\rightarrow }}_{z}\)) in a heterotrilayer device (Device A) and a heterobilayer device (Device B). Real-space PL images corresponding to anti-confinement (iii), free diffusion (iv), and confinement (v) behaviors of IXs. (vi) Peak emission energy inside and outside the gate region as a function of applied electric field, with different incident power levels represented by red and blue curves. (vii) Interlayer exciton density as a function of applied electric field, with different incident power levels shown by red and blue curves. c (i) IX diode and transistor featuring etched FLG top gates incorporating a triangular slide structure. (ii) COSMOL calculation depicting the vertical electric field component beneath the etched graphene region. (iii) CCD images capturing laser intensity (left), gates off state (middle), and gates on state (right). a Reproduced with permission [40]. Copyright [2018] Springer Nature. b Reproduced with permission [41]. Copyright [2019] Springer Nature. c Reproduced with permission [42]. Copyright [2022] Americal Chemical Society