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Dopant Induced Impurity Bands and Carrier Concentration Control for Thermoelectric Enhancement in p-Type Cr2Ge2Te6
Tang, Xiaodan1,4; Fang, Dengdong2,3; Peng, Kunling1,4; Yang, Dingfeng6; Guo, Lijie1; Lu, Xu1; Dai, Jiyan5; Wang, Guoyu4; Liu, Huijun2,3; Zhou, Xiaoyuan1
2017-09-12
摘要Our previous work demonstrated that Cr2Ge2Te6 based compounds with a layered structure and high symmetry are good candidates for thermoelectric to, application. However, the power factor of only,0.23 mW/mK(2) in 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/mK(2) to 0.57 mW/mK(2) at 830 K with x = 0.05. Combined with the intrinsic low thermal conductivity, Cr1.9Mn0.1Ge2Te6 displays 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.
DOI10.1021/acs.chemmater.7b02346
发表期刊CHEMISTRY OF MATERIALS
ISSN0897-4756
卷号29期号:17页码:7401-7407
通讯作者Zhou, XY (reprint author), Chongqing Univ, Coll Phys, Chongqing 401331, Peoples R China. ; Liu, HJ (reprint author), Wuhan Univ, Minist Educ, Key Lab Artificial Micro & Nanostruct, Wuhan 430072, Hubei, Peoples R China. ; Liu, HJ (reprint author), Wuhan Univ, Sch Phys & Technol, Wuhan 430072, Hubei, Peoples R China.
收录类别SCI
WOS记录号WOS:000410868600043
语种英语