Enhanced Power Factor and Figure of Merit of Cu2ZnSnSe4-Based Thermoelectric Composites by Ag Alloying

Fahad Mehmood; Hongchao Wang; Wenbin Su; Mahwish Khan; Taichang Huo; Tingting Chen; Galina Chebanova; Anatoly Romanenko; Chunlei Wang

doi:10.1021/acs.inorgchem.1c00079

Enhanced Power Factor and Figure of Merit of Cu₂ZnSnSe₄-Based Thermoelectric Composites by Ag Alloying

Inorg Chem. 2021 Mar 1;60(5):3452-3459. doi: 10.1021/acs.inorgchem.1c00079. Epub 2021 Feb 16.

Authors

Fahad Mehmood¹, Hongchao Wang¹, Wenbin Su¹, Mahwish Khan¹, Taichang Huo¹, Tingting Chen¹, Galina Chebanova², Anatoly Romanenko², Chunlei Wang¹

Affiliations

¹ School of Physics, State Key Laboratory of Crystal Materials, Shandong University, No. 27 Shanda South Road, Jinan 250100, People's Republic of China.
² Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia.

PMID: 33591740
DOI: 10.1021/acs.inorgchem.1c00079

Abstract

The quaternary chalcogenide composites Cu₂ZnSn_1-xAg_xSe₄ (0 ≤ x ≤ 0.075) have been successfully synthesized by high-temperature melting and annealing followed by hot-pressing. The phase structure of the bulk sample has been analyzed by powder X-ray diffraction and Rietveld refinement combined with Raman spectroscopy to confirm Cu₂ZnSnSe₄ as the main phase with ZnSe and Cu₅Zn₈ secondary phases. The thermoelectric properties of all specimens have been investigated in the temperature range of 300-700 K. The replacement of Sn by Ag significantly enhances the electrical transport properties by providing extra charge carriers. The tremendous reduction in electrical resistivity enhances the power factor, and a maximum power factor of 804 μW K^-2 m^-1 is achieved at 673 K for the specimen with 5% Ag content. Furthermore, increased point defects increase phonon scattering, resulting in reduced thermal conductivity. The combined effect of improved power factor and suppressed thermal conductivity provides a good boost to the dimensionless figure of merit. The maximum figure of merit of zT = 0.25 has been achieved at 673 K for Cu₂ZnSn_0.95Ag_0.05Se₄, which is 2.5 times the value of the parent sample.