Issue 8, 2019, Issue in Progress

Enhancement of thermoelectric properties over a wide temperature range by lattice disorder and chemical potential tuning in a (CuI)y(Bi2Te3)0.95−x(Bi2Se3)x(Bi2S3)0.05 quaternary system

Abstract

Bi2Te3-based compounds have received attention as thermoelectric materials for room-temperature cooling and waste heat recovery applications. With potential application prospects, quaternary compounds of Bi2Te3–Bi2Se3–Bi2S3 composites can be used for mid-temperature power generation under 500 °C. Herein, we investigated the thermoelectric properties of (CuI)y(Bi2Te3)0.95−x(Bi2Se3)x(Bi2S3)0.05 (x = 0.05, 0.2; y = 0.0, 0.003) compounds. Through X-ray diffraction and transmission electron microscopy, we confirmed that the lattice disorder in (Bi2Te3)0.95−x(Bi2Se3)x(Bi2S3)0.05 (x = 0.2) was due to multiple element substitutions. Disorder carrier scattering induced the localized nature of electrical resistivity, as confirmed by variable range hopping at low temperature. The temperature-dependent Seebeck coefficient of (Bi2Te3)0.95−x(Bi2Se3)x(Bi2S3)0.05 showed a carrier-type change from p- to n-type behaviour in the intermediate temperature range (525 K for x = 0.05 and 360 K for x = 0.2). Even though strong carrier localization increased electrical resistivity, resulting in degradation of the power factor and thermoelectric performance, when the chemical potential was increased to the conduction band minimum through CuI co-doping into the (CuI)0.003(Bi2Te3)0.95−x(Bi2Se3)x(Bi2S3)0.05 (x = 0.05, 0.2) compounds, the carriers were delocalized and showed n-type behaviour in the Seebeck coefficient. The temperature-dependent thermal conductivity shows the suppression of bipolar conduction behaviour. The simultaneous effect on carrier optimization through chemical potential tuning and lattice disorder caused a high ZT value of 0.85 at 523 K for CuI-doped (Bi2Te3)0.75(Bi2Se3)0.2(Bi2S3)0.05, which was comparatively high for n-type thermoelectric materials in the mid-temperature range.

Graphical abstract: Enhancement of thermoelectric properties over a wide temperature range by lattice disorder and chemical potential tuning in a (CuI)y(Bi2Te3)0.95−x(Bi2Se3)x(Bi2S3)0.05 quaternary system

Article information

Article type
Paper
Submitted
09 Nov 2018
Accepted
21 Jan 2019
First published
31 Jan 2019
This article is Open Access
Creative Commons BY license

RSC Adv., 2019,9, 4190-4197

Enhancement of thermoelectric properties over a wide temperature range by lattice disorder and chemical potential tuning in a (CuI)y(Bi2Te3)0.95−x(Bi2Se3)x(Bi2S3)0.05 quaternary system

H. Cho, S. Y. Back, J. H. Kim, O. Inturu, H. S. Lee and J. Rhyee, RSC Adv., 2019, 9, 4190 DOI: 10.1039/C8RA09280J

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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