Alternatingly Stacked Low‐ and High‐Resistance PtSe2/PtSe2 Homostructures Boost Thermoelectric Power Factors

Abstract 2D transition‐metal dichalcogenide (TMDC) materials are promising candidates with excellent thermoelectric (TE) properties owing to their low dimensionality in electronic and phonon transport. However, the considerable coupling of the Seebeck coefficient and electrical conductivity in such TE materials eventually results in the limit of the TE power factor increase, which severely hinders potential TE device applications. Herein, an alternative approach is demonstrated for breaking the strong coupling between the Seebeck coefficient and electrical conductivity in single TE materials by adopting a novel stacked PtSe 2 /PtSe 2 homostructure. By alternately piling low‐resistance (LR) PtSe 2 (3 nm) onto high‐resistance (HR) PtSe 2 (2 nm) as one unit, the Seebeck coefficient and electrical conductivity of such stacked homostructures can be greatly enhanced with slightly improved electrical conductivity, ultimately resulting in a TE power factor in three‐unit‐stacked homostructures that is ≈1,648% higher than that of a single PtSe 2 (15 nm) layer with the same thickness. This enhancement is attributed to an independent increase in the Seebeck coefficient, which depends on the interface among the LR and HR PtSe 2 layers. The findings pave the way for a method that, unlike power factor optimization in conventional thermoelectric materials, can only utilize the Seebeck coefficient and electrical conductivity of each layer in a stacked homostructure.