Fig. 1. Observation of IXs in mL-WSe₂/1L-MoS₂ and 1L-WSe₂/mL-MoS₂ heterostructures.

(A and B) A schematic of the IXs in mL-WSe₂/1L-MoS₂ and 1L-WSe₂/mL-MoS₂ heterostructures (HS), respectively. The inset shows a type II band alignment of WSe₂/MoS₂ heterostructure [intralayer exciton (X); interlayer exciton (IX)]. For IX, the electrons and holes are separated in MoS₂ and WSe₂ layers, respectively. (C and D) The optical microscope image of the mL-WSe₂/1L MoS₂ (labeled as mL/1L; m = 1 to 3) sample (S1) and 1L-WSe₂/mL-MoS₂ (labeled as 1L/mL; m = 1, 3, and 4) sample (S2). WSe₂ and MoS₂ with different layers are marked with dashed lines of different colors. The heterostructure regions are marked with solid white lines. Scale bars, 10 μm. (E) The PL spectra of intralayer excitons in monolayer WSe₂ and MoS₂ and IXs in 1L-WSe₂/1L-MoS₂ heterostructure sample at room temperature (RT). (F and G) The PL spectra of IXs in mL-WSe₂/1L-MoS₂ heterostructure and 1L-WSe₂/mL-MoS₂ heterostructure at low temperature. au, arbitrary units.