Effects of Sb Deviation from Its Stoichiometric Ratio on the Micro- and Electronic Structures and Thermoelectric Properties of Cu12Sb4S13

Lulu Huang; Yuan Kong; Jian Zhang; Chen Zhu; Jinhua Zhang; Yuanyue Li; Di Li; Hongxing Xin; Zhaoming Wang; Xiaoying Qin

doi:10.1021/acsami.0c00094

Effects of Sb Deviation from Its Stoichiometric Ratio on the Micro- and Electronic Structures and Thermoelectric Properties of Cu₁₂Sb₄S₁₃

ACS Appl Mater Interfaces. 2020 Mar 25;12(12):14145-14153. doi: 10.1021/acsami.0c00094. Epub 2020 Mar 10.

Authors

Lulu Huang^{1

2}, Yuan Kong², Jian Zhang¹, Chen Zhu^{1

2}, Jinhua Zhang^{1

2

3}, Yuanyue Li⁴, Di Li¹, Hongxing Xin¹, Zhaoming Wang¹, Xiaoying Qin¹

Affiliations

¹ Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, PR China.
² University of Science and Technology of China, Hefei 230026, China.
³ State Key Laboratory of Pulsed Power Laser Technology, National University of Defense Technology, Hefei 230037, PR China.
⁴ College of Microtechnology & Nanotechnology, Qingdao University, Qingdao 266071, China.

PMID: 32109043
DOI: 10.1021/acsami.0c00094

Abstract

Thermoelectric material tetrahedrite Cu₁₂Sb₄S₁₃ has attracted much attention because of its intrinsic low lattice thermal conductivity, excellent electrical transport property, and environment-friendly constituents. However, its thermoelectric figure merit, ZT, is limited because of the low Seebeck coefficient (S) and power factor (PF). Hence, it is indispensable to enhance its S and PF to increase its ZT. Here, we show that when Sb deviation from its stoichiometric ratio in the Cu₁₂Sb₄S₁₃ band structure is modulated, it gives rise to increased density of states and enhancement of the Seebeck coefficient. Moreover, carrier concentration is tuned by changing sulfur and copper vacancies through controlling the Cu₃SbS₄ phase with an atomic ratio of Sb, leading to increased electrical conductivity. In addition, as large as ∼60% reduction of lattice thermal conductivity is obtained by intensified phonon scattering using an impurity phase/element and vacancy-like defects induced by different Sb contents. As a result, a high ZT = 0.86 is achieved at 723 K for the Cu₁₂Sb_4+δS₁₃ sample with δ = 0.2, which is ∼50% larger than that of stoichiometric Cu₁₂Sb₄S₁₃ studied here, indicating that ZT of Cu₁₂Sb₄S₁₃ can be improved through simple modulation of the Sb stoichiometric ratio.

Keywords: Cu12Sb4S13; Rietveld refinements; density of states; power factor; thermoelectric performance.