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Ga-Doping-Induced Carrier Tuning and Multiphase Engineering in n-type PbTe with Enhanced Thermoelectric Performance

Wang, Zhengshang, Wang, Guoyu, Wang, Ruifeng, Zhou, Xiaoyuan, Chen, Zhiyu, Yin, Cong, Tang, Mingjing, Hu, Qing, Tang, Jun, Ang, Ran
ACS applied materials & interfaces 2018 v.10 no.26 pp. 22401-22407
engineering, harvesting, lead, materials science, temperature, thermal conductivity
P-type lead telluride (PbTe) emerged as a promising thermoelectric material for intermediate-temperature waste-heat-energy harvesting. However, n-type PbTe still confronted with a considerable challenge owing to its relatively low figure of merit ZT and conversion efficiency η, limiting widespread thermoelectric applications. Here, we report that Ga-doping in n-type PbTe can optimize carrier concentration and thus improve the power factor. Moreover, further experimental and theoretical evidence reveals that Ga-doping-induced multiphase structures with nano- to micrometer size can simultaneously modulate phonon transport, leading to dramatic reduction of lattice thermal conductivity. As a consequence, a tremendous enhancement of ZT value at 823 K reaches ∼1.3 for n-type Pb₀.₉₇Ga₀.₀₃Te. In particular, in a wide temperature range from 323 to 823 K, the average ZTₐᵥₑ value of ∼0.9 and the calculated conversion efficiency η of ∼13% are achieved by Ga doping. The present findings demonstrate the great potential in Ga-doped PbTe thermoelectric materials through a synergetic carrier tuning and multiphase engineering strategy.