title: Superior intrinsic thermoelectric performance with zT of 1.8 in single-crystal and melt-quenched highly dense Cu(2-x)Se bulks.
abstract: Practical applications of the high temperature thermoelectric materials developed so far are partially obstructed by the costly and complicated fabrication process. In this work, we put forward two additional important properties for thermoelectric materials, high crystal symmetry and congruent melting. We propose that the recently discovered thermoelectric material Cu2-xSe, with figure of merit, zT, over 1.5 at T of ~ 1000 K, should meet these requirements, based on our analysis of its crystal structure and the Cu-Se binary phase diagram. We found that its excellent thermoelectric performance is intrinsic, and less dependent on grain size, while highly dense samples can be easily fabricated by a melt-quenching approach. Our results reveal that the melt-quenched samples and single crystals exhibit almost the same superior thermoelectric performance, with zT as high as 1.7-1.8 at T of ~973 K. Our findings not only provide a cheap and fast fabrication method for highly dense Cu(2-x)Se bulks with superior thermoelectric performance, paving the way for possible commercialization of Cu2-xSe as an outstanding component in practical thermoelectric modules, but also provide guidance in searching for new classes of thermoelectric systems with high crystal symmetry or further improving the cost performance of other existing congruent-melting thermoelectric materials.
authors.affiliation: 1] Spintronic and Electronic Materials Group, Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, North Wollongong, 2500, Australia [2] Institute for Crystal Materials, Shandong University, Jinan, Shandong, P.R. China.
authors.forename: Lan-ling
authors.initials: LL
authors.lastname: Zhao
authors.affiliation: Spintronic and Electronic Materials Group, Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, North Wollongong, 2500, Australia.
authors.forename: Xiao-lin
authors.initials: XL
authors.lastname: Wang
authors.affiliation: Institute for Crystal Materials, Shandong University, Jinan, Shandong, P.R. China.
authors.forename: Ji-yang
authors.initials: JY
authors.lastname: Wang
authors.affiliation: Spintronic and Electronic Materials Group, Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, North Wollongong, 2500, Australia.
authors.forename: Zhen-xiang
authors.initials: ZX
authors.lastname: Cheng
authors.affiliation: Spintronic and Electronic Materials Group, Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, North Wollongong, 2500, Australia.
authors.forename: Shi-xue
authors.initials: SX
authors.lastname: Dou
authors.affiliation: Spintronic and Electronic Materials Group, Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, North Wollongong, 2500, Australia.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Faculty of Engineering, Shandong Jianzhu University, Shandong, P.R. China.
authors.forename: Li-qiang
authors.initials: LQ
authors.lastname: Liu