Fig. 1.

Sample structure and light emission at T = 300 K. a Schematic drawing of the sample. The monolayer TMD and graphene are sandwiched between two multilayer hBN flakes. b Optical microscope image of a typical sample, in this case based on WS₂. The cross marks the position at which the PL spectra were taken. Scale bar, 5 μm. c Band diagram of transient EL. On the left, the pulse voltage is at a negative value, while on the right it is at a positive value. The bottom picture schematically depicts the shape of the pulse. d Optical microscopy image of the sample while emitting light. The EL emission is generated near the interface between graphene and monolayer WS₂ due to carrier diffusion from graphene. Scale bar, 20 μm. e Photoluminescence (PL) and electroluminescence (EL) emission spectrum (excitation λ = 532 nm, P_d = 2 × 10³ Wcm⁻²). The EL spectrum closely matches the PL spectrum