Enhanced Low-Temperature Thermoelectric Performance in (PbSe)<sub>1+δ</sub>(VSe<sub>2</sub>)<sub>1</sub> Heterostructures due to Highly Correlated Electrons in Charge Density Waves.
basic_science · Level V
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- Record sourced from PubMed, PMID 33095023.
- Also identified by DOI 10.1021/acs.nanolett.0c02882.
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Abstract
We explore the effect of charge density wave (CDW) on the in-plane thermoelectric transport properties of (PbSe)<sub>1+δ</sub>(VSe<sub>2</sub>)<sub>1</sub> and (PbSe)<sub>1+δ</sub>(VSe<sub>2</sub>)<sub>2</sub> heterostructures. In (PbSe)<sub>1+δ</sub>(VSe<sub>2</sub>)<sub>1</sub> 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)<sub>1+δ</sub>(VSe<sub>2</sub>)<sub>2</sub> 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)<sub>1+δ</sub>(VSe<sub>2</sub>)<sub>1</sub> material show the emergence of additional peaks below the CDW transition temperature associated with VSe<sub>2</sub> material. Temperature-dependent in-plane X-ray diffraction (XRD) spectra show a change in the in-plane thermal expansion of VSe<sub>2</sub> in (PbSe)<sub>1+δ</sub>(VSe<sub>2</sub>)<sub>1</sub> 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.