Interface-Induced Seebeck Effect in PtSe 2 /PtSe 2 van der Waals Homostructures.

The Seebeck effect refers to the production of an electric voltage when different temperatures are applied on a conductor, and the corresponding voltage-production efficiency is represented by the Seebeck coefficient. We report a Seebeck effect: thermal generation of driving voltage from the heat flowing in a thin PtSe 2 /PtSe 2 van der Waals homostructure at the interface. We refer to the effect as the interface-induced Seebeck effect. By exploiting this effect by directly attaching multilayered PtSe 2 over high-resistance PtSe 2 thin films as a hybridized single structure, we obtained the highly challenging in-plane Seebeck coefficient of the PtSe 2 films that exhibit extremely high resistances. This direct attachment further enhanced the in-plane thermal Seebeck coefficients of the PtSe 2 /PtSe 2 van der Waals homostructure on sapphire substrates. Consequently, we successfully enhanced the in-plane Seebeck coefficients for the PtSe 2 (10 nm)/PtSe 2 (2 nm) homostructure approximately 42% compared to that of a pure PtSe 2 (10 nm) layer at 300 K. These findings represent a significant achievement in understanding the interface-induced Seebeck effect and provide an effective strategy for promising large-area thermoelectric energy harvesting devices using two-dimensional transition metal dichalcogenide materials, which are ideal thermoelectric platforms with high figures of merit.