Enhanced Thermoelectric Performance of van der Waals Tellurium via Vacancy Engineering

Abstract Elemental doping is essential for tuning thermoelectric properties. However, effective doping has been a challenging task particularly for low dimensional materials. Here we demonstrate a vacancy-engineering strategy for effective doping to enhance thermoelectric properties of two-dimensional (2D) materials, using van der Waals tellurium as an example. Both Density Functional Theory (DFT) calculations and temperature dependent thermoelectric measurements confirm that annealing-induced vacancies can effectively shift the Fermi level into the valance band of individual 2D tellurium nanosheets, and consequentially increase the electrical conductivity significantly from 7×103 Sm-1 to 2.7×104 Sm-1. As a result, this vacancy-engineering induced self-doping effect yields a state of art thermoelectric figure-of-merit (ZT) of 0.4 at 400 K. Therefore, our work provides an alternative and promising pathway for tuning the thermoelectric properties desirable for low dimensional materials.