Stabilizing the Optimal Carrier Concentration in Al/Sb-Codoped GeTe for High Thermoelectric Performance
Xinyu Wang, Wenhua Xue, Zongwei Zhang, Xiaofang Li, Li Yin, Chen Chen, Bo Yu, Jiehe Sui, Feng Cao, Xingjun Liu, Jun Mao, Yumei Wang, Xi Lin, Qian Zhang
Abstract
GeTe is a promising thermoelectric material and has attracted growing research interest recently. In this study, the effect of Al doping and Al&Sb codoping on the thermoelectric properties of GeTe was investigated. Due to the presence of a high concentration of intrinsic Ge vacancies, pristine GeTe exhibited a very high hole concentration and unpromising thermoelectric performance. By Sb doping in GeTe, the hole concentration can be effectively reduced, thus improving the thermoelectric performance. Aluminum, as a p-type dopant in GeTe, will increase the hole concentration and lattice thermal conductivity; thus, it has long been considered as an unfavorable dopant for the optimization of GeTe-based materials. However, when Al and Sb were codoped into GeTe, the hole concentration was effectively suppressed, and the lattice thermal conductivity can be reduced. Eventually, a maximum zT of ∼2.0 at 773 K was achieved in Al&Sb-codoped Al0.01Sb0.1Ge0.89Te.