a, Bright-field image of a fully encapsulated MoSe 2 /WS 2 sample S1; the points for which we report the photoluminescence and reflectance contrast spectra in b–d are marked. Scale bar, 10 μm. b–d, Low-temperature photoluminescence (black) and reflectance contrast (red) spectra recorded in several regions of the sample marked in a. The two higher-energy peaks in the photoluminescence spectra, X∗ at 1.624 and X A at 1.652 eV, correspond to trion and excition emission unintentionally collected from the single-layer MoSe 2 area located at the right side of the heterobilayer region. The position of these peaks remains unchanged in all three points, while their intensity decreases gradually with the increasing spatial separation. The two lower-energy photoluminescence peaks, labelled hX∗ and hX 1 , represent the emission originating in the heterostructure region and show variation in position and relative intensities across the heterostructure region, probably caused by the non-uniform strain and doping. The reflectance contrast spectra recorded at the three points are similar, with the two lower-energy peaks directly corresponding to hX∗ and hX 1 in the photoluminescence spectra, and hX 2 and hX 3 representing the higher-energy states. e, Comparison of low-temperature photoluminescence spectra recorded in the samples fabricated from mechanically exfoliated monolayers. Dashed lines show photoluminescence spectra of uncoupled single-layer MoSe 2 , recorded in the same sample, in which an uncoupled MoSe 2 monolayer area was present. Samples S1–S4 were fabricated with the crystal axes of the two materials closely aligned, whereas sample S5 was made with a considerable rotational misalignment (θ = 12°). Despite the variation of exciton (X A ) and trion (X∗) energies, all four aligned samples show a hybridized exciton peak hX 1 , located 20–30 meV lower in energy than the monolayer trion line. Samples S1 and S2 show an additional lower-energy line hX∗ positioned approximately 32 meV lower in energy than hX 1 . Figure 4 reports data for the closely aligned sample S1 and the misaligned sample S5. Figure 5 reports data for sample S1. Source data