The Effects of Te2− and I Substitutions on the Electronic Structures, Thermoelectric Performance, and Hardness in Melt-Quenched Highly Dense Cu2-xSe

Lanling Zhao, Xiaolin Wang*, Frank F. Yun, Jiyang Wang, Zhenxiang Cheng, Shixue Dou, Jun Wang, G. Jeffrey Snyder

*Corresponding author for this work

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

A systematic study has been carried out on the electronic band structure and density of states, crystal structures, thermoelectric properties, and hardness of the Cu2-xSe system with and without Te2− or I substitutions for Se2−. Density functional theory calculations indicate that stoichiometric Cu2Se is a zero-gap material, and copper-deficient Cu1.875Se is a p-type conductor. Te2– substitution increases the total density of states at the Fermi level, whereas, the I substitution leads to the reduction of the total and partial density of states for both Se and Cu. Highly dense undoped, Te-doped, and I-doped Cu2-xSe bulks have been fabricated by a melt-quenching method which only takes a few minutes. Rietveld refinements of the X-ray diffraction patterns reveal that the unit cells are expanded after doping. All the fabricated bulks are p-type conductors in accordance with band structure calculations, and they all have figure of merit, zT, values over or close to 1.0 at T = 973 K, except for the Cu2-xTe0.16Se0.84. Furthermore, the hardness is distinctly improved by the doping approach, with a maximum value of ca. 0.66 GPa for the Cu2-xTe0.16Se0.84, which is higher than those of polycrystalline Bi2Te3 and PbTe bulks.

Original languageEnglish (US)
Article number1400015
JournalAdvanced Electronic Materials
Volume1
Issue number3
DOIs
StatePublished - Jan 1 2015

Keywords

  • cuprous selenide
  • electronic band structure
  • hardness
  • thermoelectricity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

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