Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 13, Issue 41, Pages 49027-49042Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.1c14236
Keywords
thermoelectric properties; energy conversion; electronic structure; thermal conductivity; Tl resonant dopant; lead telluride
Funding
- Foundation for Polish Science [TEAM-TECH/2016-2/14]
- European Union under the European Regional Development Fund
- National Science Centre (Poland) [2017/26/E/ST3/00119]
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This study demonstrates the simultaneous enhancement of electrical transport and reduction of phonon propagation in p-type PbTe codoped with Tl and Na. By utilizing advanced electronic structure engineering, the thermoelectric power factor was improved, resulting in significantly enhanced electrical conductivity and Seebeck coefficient. The combination of impurity resonance scattering and crystal lattice softening led to a high ZT value, showing the potential for advancing thermoelectrics.
In this work, we show the simultaneous enhancement of electrical transport and reduction of phonon propagation in p-type PbTe codoped with Tl and Na. The effective use of advanced electronic structure engineering improves the thermoelectric power factor S-2 sigma over the temperature range from 300 to 825 K. A rise in the Seebeck coefficient S was obtained due to the enhanced effective mass m*, coming from the Tl resonance state in PbTe. Due to the presence of additional carriers brought by Na codoping, electrical conductivity became significantly improved. Furthermore, Tl and Na impurities induced crystal lattice softening, remarkably reducing lattice thermal conductivity, which was confirmed by a measured low speed of sound v(m) and high internal strain CeXRD. Eventually, the combination of both the attuned electronic structure and the lattice softening effects led to a very high ZT value of up to similar to 2.1 for the Pb1-x-yTlxNayTe samples. The estimated energy conversion efficiency shows the extraordinary value of 15.4% (T-c = 300 K, T-h = 825 K), due to the significantly improved average thermoelectric figure of merit Z(Tave) = 1.05. This work demonstrates that the combination of impurity resonance scattering and crystal lattice softening can be a breakthrough concept for advancing thermoelectrics.
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