Excellent thermoelectric performance of ZrTe2 thin films and device

Abstract

Achieving high thermoelectric power factor in thin film heterostructures is essential for integrated and miniatured thermoelectric device applications. In this work, we demonstrate a mechanism and device performance of enhanced thermoelectric power factor through coupling the interfacial confined two-dimensional electron gas (2DEG) with thin film conductivity in a transition metal dichalcogenides-SrTiO3 heterostructure. Owing to the formed conductive interface with two-dimensional electron confinement effect and the elevated conductivity, the ZrTe2/SrTiO3 (STO) heterostructure presents enormous thermoelectric power factor as high as 4×10^5 μW/cmK^2 at 20 K and 4800 μW/cmK^2 at room temperature. Formation of quasi-two-dimensional electrons gas at the interface is attributed to the giant Seebeck coefficient, and enhanced electrical conductivity is suggested to be originated from charge transfer induced doping in the ZrTe2, which leads to extremely large thermoelectric power factor. By taking the thermal conductivity of STO substrate as a reference, the effective zT value of this heterostructure can reach 1.5 at 300 K. This high thermoelectric figure of merit is demonstrated by a prototype device based on this heterostructure which results in 3K temperature cooling by passing through a current of 100 mA. This superior thermoelectric property makes this heterostructure a promising candidate for future thermoelectric device, and more importantly, paves a new pathway to design promising high-performance thermoelectric systems.