TY - JOUR
T1 - Dopant Induced Impurity Bands and Carrier Concentration Control for Thermoelectric Enhancement in p-Type Cr2Ge2Te6
AU - Tang, Xiaodan
AU - Fan, Dengdong
AU - Peng, Kunling
AU - Yang, Dingfeng
AU - Guo, Lijie
AU - Lu, Xu
AU - Dai, Jiyan
AU - Wang, Guoyu
AU - Liu, Huijun
AU - Zhou, Xiaoyuan
PY - 2017/9/12
Y1 - 2017/9/12
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85029311094&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.7b02346
DO - 10.1021/acs.chemmater.7b02346
M3 - Journal article
SN - 0897-4756
VL - 29
SP - 7401
EP - 7407
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 17
ER -