Enhanced Terahertz Thermoelectricity Via Engineered Van Hove Singularities and Nernst Effect in Moiré Superlattices

ABSTRACT Thermoelectric materials, long explored for energy harvesting and thermal sensing, convert heat directly into electrical signals. Extending their application to the terahertz (THz) frequency range opens opportunities for low‐noise, bias‐free THz detection, yet conventional thermoelectrics lack the sensitivity required for practical devices. Thermoelectric coefficients can be strongly enhanced near van Hove singularities (VHS), though these are usually difficult to access in conventional materials. Here it is shown that moiré band engineering unlocks these singularities for THz optoelectronics. Using graphene and bilayer graphene/hexagonal boron nitride (hBN) moiré heterostructures as a model system, a pronounced enhancement of the THz photothermoelectric response is observed when the Fermi level is tuned to band‐structure singularities. Applying a relatively small magnetic field further boosts the response through the THz‐driven Nernst effect, a transverse thermoelectric current driven by the THz‐induced temperature gradient. These results establish moiré superlattices as a versatile platform for THz thermoelectricity and highlight engineered band structures as a route to high‐performance THz optoelectronic devices.