Enhanced Low-Temperature Thermoelectric Performance In (Pbse)(1+Delta)(Vse2)(1) Heterostructures Due To Highly Correlated Electrons In Charge Density Waves

We explore the effect of charge density wave (CDW) on the in-plane thermoelectric transport properties of (PbSe)(1+delta)(VSe2)(1) and (PbSe)(1+delta)(VSe2)(2) heterostructures. In (PbSe)(1+delta)(VSe2)(1) we observe an abrupt 86% increase in the Seebeck coefficient, 245% increase in the power factor, and a slight decrease in resistivity over the CDW transition. This behavior is not observed in (PbSe)(1+delta)(VSe2)(2) and is rather unusual compared to the general trend observed in other materials. The abrupt transition causes a deviation from the Mott relationship through correlated electron states. Raman spectra of the (PbSe)(1+delta)(VSe2)(1) material show the emergence of additional peaks below the CDW transition temperature associated with VSe2 material. Temperature-dependent in-plane X-ray diffraction (XRD) spectra show a change in the in-plane thermal expansion of VSe2 in (PbSe)(1+delta)(VSe2)(1) due to lattice distortion. The increase in the power factor and decrease in the resistivity due to CDW suggest a potential mechanism for enhancing the thermoelectric performance at the low temperature region.