Enhancement of thermoelectric performance by tuning selenium content in the Cu2SnSe3 compound. (July 2020)

• Record Type: Journal Article
• Authors: Gurukrishna, K.; Rao, Ashok; Jiang, Zhao-Ze; Kuo, Yung-Kang
• Is Part Of: Intermetallics. Volume 122(2020:Jul.)
• Publication Date: 2020-07
• Subjects: Functional alloys -- Thermoelectric properties -- Powder metallurgy -- Point defects; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2020.106803
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: To investigate the thermoelectric properties, we have attempted to tune selenium content in Cu2 SnSe3- δ (−0.04 ≤ δ ≤ 0.1) compounds synthesized via the conventional solid-state reaction. Electrical and thermal properties are presented in the low and near room temperature regime (10–350 K). The lowest electrical resistivity is observed for the compound with δ = 0.08. The electron-phonon coupling and the presence of small polarons are experimentally validated from temperature-dependent electrical and thermal transport data. A decrease in the Seebeck coefficient along with carrier concentration is observed, verifying the linear electron band dispersion. A downward shift of the Fermi level deep into the valence band is realized in the case of non-stoichiometric samples, thereby reducing the Seebeck coefficient. A maximum power factor of ~50 μWmK −2 is achieved for the sample with δ = 0.04, which is about twice that of the pristine compound. The highest ZT of ~0.01 is obtained for the compound with δ = 0.08. The observed results suggest that stoichiometry plays a vital role in tuning the thermoelectric properties in the Cu2 SnSe3 compound. Graphical abstract: Image 1 Highlights: Non-stoichiometry tunes both the power factor and figure of merit. Samples crystallize in cubic sphalerite type structure. Existence of small polarons is established by temperature dependent resistivity trend. Transport properties obey electron band dispersion model. Relaxation time approximation model is valid at room temperature.