Dopant Induced Impurity Bands and Carrier Concentration Control for Thermoelectric Enhancement in p-Type Cr2Ge2Te6

Xiaodan Tang, Dengdong Fan, Kunling Peng, Dingfeng Yang, Lijie Guo, Xu Lu, Jiyan Dai, Guoyu Wang, Huijun Liu, Xiaoyuan Zhou

Research output: Journal article publicationJournal articleAcademic researchpeer-review

24 Citations (Scopus)

Abstract

Our previous work demonstrated that Cr2Ge2Te6based compounds with a layered structure and high symmetry are good candidates for thermoelectric application. However, the power factor of only ∼0.23 mW/mK2in undoped material is much lower than that of conventional thermoelectrics. This indicates the importance of an electronic performance optimization for further improvements. In this work, either Mn- or Fe-substitution on the Cr site is investigated, with expectations of both carrier concentration control and band structure engineering. First-principle calculations indicate that an orbital hybridization between d orbitals of the doping atom and the p orbital of Te significantly increases the density of states (DOS) around the Fermi level. In addition, it is found that Mn doping is more favorable to improve the electrical properties than Fe doping. By tuning the carrier concentration via Mn doping, the peak power factor rises rapidly from 0.23 mW/mK2to 0.57 mW/mK2at 830 K with x = 0.05. Combined with the intrinsic low thermal conductivity, Cr1.9Mn0.1Ge2Te6displays a decent zT of 0.63 at 833 K, a 2-fold value as compared to that of the undoped sample at the same direction and temperature.
Original languageEnglish
Pages (from-to)7401-7407
Number of pages7
JournalChemistry of Materials
Volume29
Issue number17
DOIs
Publication statusPublished - 12 Sep 2017

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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