Fine tuning of defects enables high carrier mobility and enhanced thermoelectric performance of n-type PbTe

Journal Article | Epub ahead of print | English

Scopus indexed
Wang, Siqi; Chang, ChengISTA ; Bai, Shulin; Qin, Bingchao; Zhu, Yingcai; Zhan, Shaoping; Zheng, Junqing; Tang, Shuwei; Zhao, Li Dong
High carrier mobility is critical to improving thermoelectric performance over a broad temperature range. However, traditional doping inevitably deteriorates carrier mobility. Herein, we develop a strategy for fine tuning of defects to improve carrier mobility. To begin, n-type PbTe is created by compensating for the intrinsic Pb vacancy in bare PbTe. Excess Pb2+ reduces vacancy scattering, resulting in a high carrier mobility of ∼3400 cm2 V–1 s–1. Then, excess Ag is introduced to compensate for the remaining intrinsic Pb vacancies. We find that excess Ag exhibits a dynamic doping process with increasing temperatures, increasing both the carrier concentration and carrier mobility throughout a wide temperature range; specifically, an ultrahigh carrier mobility ∼7300 cm2 V–1 s–1 is obtained for Pb1.01Te + 0.002Ag at 300 K. Moreover, the dynamic doping-induced high carrier concentration suppresses the bipolar thermal conductivity at high temperatures. The final step is using iodine to optimize the carrier concentration to ∼1019 cm–3. Ultimately, a maximum ZT value of ∼1.5 and a large average ZTave value of ∼1.0 at 300–773 K are obtained for Pb1.01Te0.998I0.002 + 0.002Ag. These findings demonstrate that fine tuning of defects with <0.5% impurities can remarkably enhance carrier mobility and improve thermoelectric performance.
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Chemistry of Materials
The National Key Research and Development Program of China (2018YFA0702100), the Basic Science Center Project of the National Natural Science Foundation of China (51788104), the National Natural Science Foundation of China (51571007 and 51772012), the Beijing Natural Science Foundation (JQ18004), the 111 Project (B17002), the National Science Fund for Distinguished Young Scholars (51925101), and the FWF “Lise Meitner Fellowship” (grant agreement M2889-N). Open Access is funded by the Austrian Science Fund (FWF).
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