Fig. 1.

a Cryogenic PL (gray) and DR (blue) spectra of a vertical MoSe₂-WSe₂ stack with dominant features of the heterobilayer (HBL) peak in emission and intralayer excitons in absorption. b Degree of circular PL polarization, P_C, under circularly polarized excitation. c Zoom-in to the intralayer exciton emission and absorption with energies of zero-momentum bright and gray excitons, IX_B and IX_G, and momentum-dark spin-like and spin-unlike excitons, IX_L and IX_U, indicated by dashed lines. The onset of absorption in the DR spectrum at ~1.37 eV stems from the inhomogenously broadened gray interlayer exciton state IX_G