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Title: AgI alloying in SnTe boosts the thermoelectric performance via simultaneous valence band convergence and carrier concentration optimization

Abstract

SnTe, a Pb-free analogue of PbTe, was earlier assumed to be a poor thermoelectric material due to excess p-type carrier concentration and large energy separation between light and heavy hole valence bands. Here, we report the enhancement of the thermoelectric performance of p-type SnTe by Ag and I co-doping. AgI (1–6 mol%) alloying in SnTe modulates its electronic structure by increasing the band gap of SnTe, which results in decrease in the energy separation between its light and heavy hole valence bands, thereby giving rise to valence band convergence. Additionally, iodine doping in the Te sublattice of SnTe decreases the excess p-type carrier concentration. Due to significant decrease in hole concentration and reduction of the energy separation between light and heavy hole valence bands, significant enhancement in Seebeck coefficient was achieved at the temperature range of 600–900 K for Sn{sub 1−x}Ag{sub x}Te{sub 1−x}I{sub x} samples. A maximum thermoelectric figure of merit, zT, of ~1.05 was achieved at 860 K in high quality crystalline ingot of p-type Sn{sub 0.95}Ag{sub 0.05}Te{sub 0.95}I{sub 0.05}. - Graphical abstract: Significant decrease in hole concentration and reduction of the energy separation between light and heavy hole valence bands resulted in a maximum thermoelectric figure of merit,more » zT, of ~1.05 at 860 K in high quality crystalline ingot of p-type Sn{sub 0.95}Ag{sub 0.05}Te{sub 0.95}I{sub 0.05}. - Highlights: • AgI alloying in SnTe increases the principle band gap. • Hole concentration reduction and valence band convergence enhances thermopower of SnTe-AgI. • A maximum zT of ~1.05 was achieved at 860 K in p-type Sn{sub 0.95}Ag{sub 0.05}Te{sub 0.95}I{sub 0.05}.« less

Authors:
;
Publication Date:
OSTI Identifier:
22658055
Resource Type:
Journal Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 242; Journal Issue: Part 2; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0022-4596
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABUNDANCE; CONCENTRATION RATIO; CONVERGENCE; DOPED MATERIALS; ELECTRONIC STRUCTURE; EXPERIMENTAL DATA; MONOCRYSTALS; PERFORMANCE; SILVER IODIDES; TEMPERATURE RANGE 0400-1000 K; THERMOELECTRIC MATERIALS; TIN TELLURIDES; VALENCE

Citation Formats

Banik, Ananya, and Biswas, Kanishka. AgI alloying in SnTe boosts the thermoelectric performance via simultaneous valence band convergence and carrier concentration optimization. United States: N. p., 2016. Web. doi:10.1016/J.JSSC.2016.02.012.
Banik, Ananya, & Biswas, Kanishka. AgI alloying in SnTe boosts the thermoelectric performance via simultaneous valence band convergence and carrier concentration optimization. United States. doi:10.1016/J.JSSC.2016.02.012.
Banik, Ananya, and Biswas, Kanishka. Sat . "AgI alloying in SnTe boosts the thermoelectric performance via simultaneous valence band convergence and carrier concentration optimization". United States. doi:10.1016/J.JSSC.2016.02.012.
@article{osti_22658055,
title = {AgI alloying in SnTe boosts the thermoelectric performance via simultaneous valence band convergence and carrier concentration optimization},
author = {Banik, Ananya and Biswas, Kanishka},
abstractNote = {SnTe, a Pb-free analogue of PbTe, was earlier assumed to be a poor thermoelectric material due to excess p-type carrier concentration and large energy separation between light and heavy hole valence bands. Here, we report the enhancement of the thermoelectric performance of p-type SnTe by Ag and I co-doping. AgI (1–6 mol%) alloying in SnTe modulates its electronic structure by increasing the band gap of SnTe, which results in decrease in the energy separation between its light and heavy hole valence bands, thereby giving rise to valence band convergence. Additionally, iodine doping in the Te sublattice of SnTe decreases the excess p-type carrier concentration. Due to significant decrease in hole concentration and reduction of the energy separation between light and heavy hole valence bands, significant enhancement in Seebeck coefficient was achieved at the temperature range of 600–900 K for Sn{sub 1−x}Ag{sub x}Te{sub 1−x}I{sub x} samples. A maximum thermoelectric figure of merit, zT, of ~1.05 was achieved at 860 K in high quality crystalline ingot of p-type Sn{sub 0.95}Ag{sub 0.05}Te{sub 0.95}I{sub 0.05}. - Graphical abstract: Significant decrease in hole concentration and reduction of the energy separation between light and heavy hole valence bands resulted in a maximum thermoelectric figure of merit, zT, of ~1.05 at 860 K in high quality crystalline ingot of p-type Sn{sub 0.95}Ag{sub 0.05}Te{sub 0.95}I{sub 0.05}. - Highlights: • AgI alloying in SnTe increases the principle band gap. • Hole concentration reduction and valence band convergence enhances thermopower of SnTe-AgI. • A maximum zT of ~1.05 was achieved at 860 K in p-type Sn{sub 0.95}Ag{sub 0.05}Te{sub 0.95}I{sub 0.05}.},
doi = {10.1016/J.JSSC.2016.02.012},
journal = {Journal of Solid State Chemistry},
issn = {0022-4596},
number = Part 2,
volume = 242,
place = {United States},
year = {2016},
month = {10}
}