Oral: Ultralow lattice thermal conductivity in twisted CrI₃/1T-MoS₂ van der Waals heterostructure.

Van der Waals heterostructures of magnetic and non-magnetic monolayers can facilitate thermoelectric transport properties [1]. The manifestation of local twist effect leads to the global electronic structure modulation via charge reconfiguration alongwith electron confinement. Here, we study thermoelectric properties of the designed magnetic CrI₃/1T-MoS₂ moiré superlattices using first principle-based density functional theory [2]. The system exhibits augmented interfacial charge transport via large built-in electrostatic potential, which endorses metal to semiconductor transitions with varying twist angles. Moreover, the electron localization function further validates the observed electron gas characteristics. The low effective mass and large spin splitting at conduction band minimum and valance band maximum alongwith superior spin-charge redistribution leads to augmented thermoelectric behaviours. In this regard, a large figure of merit (=4.3) is estimated at 30°, which makes the heterostructure an ideal candidate for thermoelectric device applications. Accordingly, ultralow lattice thermal conductivity of the order 0.0023 is calculated, which underpins the observed large Seebeck coefficient (413 μV/K) at 30°. Hence, moiré superlattices offer an exceptional platform with utmost efficiency to realize direct conversion of waste heat into electrical energy.