A Thermoelectric Performance Study of Layered Bi2TeI Weak Topological Insulator Materials

Abstract

Topological insulators have been considered as promising thermoelectric materials because of their high electrical transport properties and low thermal conductivity. In this work, the crystal structure, chemical composition, and thermoelectric transport properties of a weak topological insulator, Bi2TeI, were studied. Bi2TeI possesses the lowest lattice thermal conductivity compared with the analogously layered compounds Bi2Te3 and BiTeI. Cu and Zn were used as dopants with the aim of optimizing the thermoelectric performance. It was found that doping Bi2TeI with Cu led to decreased carrier concentration and power factor while doping with Zn resulted in increased carrier concentration and improved power factor. Accompanied with reduced lattice thermal conductivity, Zn-doped samples showed a largely improved dimensionless figure of merit, ZT. The largest ZT was 0.077 for Zn0.01Bi2TeI, increased by 70% as compared with the undoped Bi2TeI.