Twist-Dependent Intra- and Interlayer Excitons in Moiré <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>MoSe</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> Homobilayers

Abstract

Optoelectronic properties of van der Waals homostructures can be selectively engineered by the relative twist angle between layers. Here, we study the twist-dependent moir\'e coupling in ${\mathrm{MoSe}}_{2}$ homobilayers. For small angles, we find a pronounced redshift of the $\mathbf{K}\text{\ensuremath{-}}\mathbf{K}$ and $\mathbf{\ensuremath{\Gamma}}\text{\ensuremath{-}}\mathbf{K}$ excitons accompanied by a transition from $\mathbf{K}\text{\ensuremath{-}}\mathbf{K}$ to $\mathbf{\ensuremath{\Gamma}}\text{\ensuremath{-}}\mathbf{K}$ emission. Both effects can be traced back to the underlying moir\'e pattern in the ${\mathrm{MoSe}}_{2}$ homobilayers, as confirmed by our low-energy continuum model for different moir\'e excitons. We identify two distinct intralayer moir\'e excitons for $R$ stacking, while $H$ stacking yields two degenerate intralayer excitons due to inversion symmetry. In both cases, bright interlayer excitons are found at higher energies. The performed calculations are in excellent agreement with experiment and allow us to characterize the observed exciton resonances, providing insight about the layer composition and relevant stacking configuration of different moir\'e exciton species.

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