Remarkable Roles of Cu To Synergistically Optimize Phonon and Carrier Transport in n-Type PbTe-Cu2Te
2017
Xiao, Yu | Wu, Haijun | Li, Wei | Yin, Meijie | Pei, Yanling | Zhang, Yang | Fu, Liangwei | Chen, Yuexing | Pennycook, Stephen J. | Huang, Li | He, Jiaqing | Zhao, Li-Dong
High thermoelectric performance of n-type PbTe is urgently needed to match its p-type counterpart. Here, we show a peak ZT ∼ 1.5 at 723 K and a record high average ZT > 1.0 at 300–873 K realized in n-type PbTe by synergistically suppressing lattice thermal conductivity and enhancing carrier mobility by introducing Cu₂Te inclusions. Cu performs several outstanding roles: Cu atoms fill the Pb vacancies and improve carrier mobility, contributing to an unexpectedly high power factor of ∼37 μW cm–¹ K–² at 423 K; Cu atoms filling Pb vacancies and Cu interstitials both induce local disorder and, together with nano- and microscale Cu-rich precipitates and their related strain fields, lead to a very low lattice thermal conductivity of ∼0.38 Wm–¹ K–¹ in PbTe-5.5%Cu₂Te, approaching the theoretical minimum value of ∼0.36 Wm–¹ K–¹. This work provides an effective strategy to enhance thermoelectric performance by simultaneously improving electrical and thermal transport properties.
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