Resonant coulomb energy transfer in transition metal dichalcogenide moirés

We report on a theoretical study of Coulomb-mediated energy transfer between electrically isolated transition metal dichalcogenide (TMD) moirés. We discuss two distinct models (approximations) intended to be accurate when the inter-moiré Coulomb interaction is either strong or weak compared to the moiré bandwidth. In the former case, which occurs when the inter-moiré spacing d is smaller than the moiré lattice constant a_M and the twist angle θ≤2º, inter-moiré energy transfer arises from interactions between nearby pairs of artificial molecules--sites of the moiré lattice where low-energy moiré band states localize. In the latter case, which occurs when θ≥2º, we describe the energy transfer with a Fermi's golden expression rule based on the random phase approximation for inter-moiré two-particle scattering amplitudes. Due to a competition between moiré lattice site densities and bandwidths, the energy transfer rate is maximized at twist angles θ≈4º, at which an interfacial thermal conductance G on the order of 100 MW/(m²K) is achievable. We relate our models of the strong and weak coupling regimes to models of the analogous regimes in photosynthetic, intermolecular energy transfer.