Y2Te3: A New n‑Type Thermoelectric Material

• Published in: ACS applied materials & interfaces Vol. 14; no. 38; pp. 43517 - 43526
• Main Authors: Toriyama, Michael Y., Cheikh, Dean, Bux, Sabah K., Snyder, G. Jeffrey, Gorai, Prashun
• Format: Journal Article
• Language: English
• Published: American Chemical Society 28-09-2022
• Subjects: Functional Inorganic Materials and Devices; dopants; chalcogenide; thermoelectrics; electrical transport; defects
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.2c12112

Rare-earth chalcogenides Re 3–x Ch 4 (Re = La, Pr, Nd, Ch = S, Se, and Te) have been extensively studied as high-temperature thermoelectric (TE) materials owing to their low lattice thermal conductivity (κL) and tunable electron carrier concentration via cation vacancies. In this work, we introduce Y2Te3, a rare-earth chalcogenide with a rocksalt-like vacancy-ordered structure, as a promising n-type TE material. We computationally evaluate the transport properties, optimized TE performance, and doping characteristics of Y2Te3. Combined with a low κL, multiple low-lying conduction band valleys yield a high n-type TE quality factor. We find that a maximum figure of merit zT > 1 can be achieved when Y2Te3 is optimally doped to an electron concentration of 1–2 × 1020 cm–3. We use defect calculations to show that Y2Te3 is n-type dopable under Y-rich growth conditions, which suppress the formation of acceptor-like cation vacancies. Furthermore, we propose that optimal n-type doping can be achieved with halogens (Cl, Br, and I), with I being the most effective dopant. Our computational results as well as experimental results reported elsewhere motivate further optimization of Y2Te3 as an n-type TE material.