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.
Highlights
Thermoelectric (TE) technology can realize direct energy conversion between heat and electricity, having played an important role in the field of waste heat recovering, power generation, and efficient cooling [1]
Theoretical calculations have shown that the TE performance of strong topological insulators (TIs) such as Bi2 Te3 and Bi2 Se3 can be enhanced by the surface state hybridization with bulk states [13], or by the largely varied electron scattering rates spanning from the surface states to the bulk states [14]
As guided with the solid-state equilibria of Bi-Te-I systems [25,26,27], polycrystalline Bi2 TeI bulk samples were synthesized using a combination of melting, annealing, and spark plasma sintering (SPS) techniques in this work
Summary
Thermoelectric (TE) technology can realize direct energy conversion between heat and electricity, having played an important role in the field of waste heat recovering, power generation, and efficient cooling [1]. Theoretical calculations have shown that the TE performance of strong TIs such as Bi2 Te3 and Bi2 Se3 can be enhanced by the surface state hybridization with bulk states [13], or by the largely varied electron scattering rates spanning from the surface states to the bulk states [14]. These studies have provided more opportunities to explore potential TE candidates among the TI systems. Bi2 TeI with Zn could improve the TE properties with enhanced electrical conductivity and Seebeck coefficient and depressed thermal conductivity
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