Defect engineering synergistically modulates power factor and thermal conductivity of CuGaTe2 for ultra-high thermoelectric performance. (20th November 2022)

• Record Type: Journal Article
• Authors: Zhang, Zipei; Li, Wenhao; Yu, Lu; Wei, Sitong; Wei, Shikai; Ji, Zhen; Song, Weiyu; Zheng, Shuqi
• Is Part Of: Journal of materials science & technology. Volume 128(2022)
• Page Start: 213
• Page End: 220
• Publication Date: 2022-11-20
• Subjects: Thermoelectric -- CuGaTe2 -- Carrier concentration -- Thermal conductivity; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2022.04.019
• Languages: English
• ISSNs: 1005-0302

Abstract

Highlights: The vacancy of Cu atom can increase the band gap and reduce the sound velocity. Cu vacancies increase the density of the samples, and significantly increase the carrier concentration. Cu vacancies generate many defects, which scatter phonons at multiple scales and realize thermoelectric decoupling. The highest ZT value of Cu0.96 GaTe2 reaches 1.23 at 823 K, and the average ZT value reaches 0.575. Abstract: The ternary chalcopyrite CuGaTe2 has emerged as a promising p -type thermoelectric material with its advantages of low cost, good stability, and non-toxic elements. However, its thermoelectric performance is limited by the intrinsic low electrical conductivity and high lattice thermal conductivity. In this work, A deficiency of Cu in Cu1– x GaTe2 semiconductors can be used to optimize the electrical properties by improving the carrier concentration and to reduce thermal conductivity through multi-scale phonon scattering, which is predicted and guided by the First-principles density functional theory calculations. The carrier concentration is increased to 10 20, which compensates for the low electrical performance caused by the intrinsic low n H of CuGaTe2 . The average power factor of Cu0.96 GaTe2 reaches 106.3% higher than that of the original CuGaTe2 . In addition, the lattice thermal conductivity of the defective samples is greatly reduced at high temperatures, which is mainly due to the reduction of sound speed and phonon scattering. All the above factors contribute to the highest dimensionless figure of merit (ZT) value of 1.23 at 823 K in Cu0.96 GaTe2, which is 114% higher than the pristine CuGaTe2, and the average ZT is 171.4% higher. Graphical abstract: Image, graphical abstract