Journal
ACS NANO
Volume 13, Issue 4, Pages 3806-3815Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.8b08579
Keywords
thermoelectric; bulk composite; Anderson localization; thermal conductivity; figure-of-merit
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Funding
- Materials and Components Technology Development Program of MOTIE/KEIT, Republic of Korea [10063286]
- Kyung Hee University [20171203]
- Korea Institute of Energy Technology Evaluation and Planning (KETEP)
- Ministry of Trade, Industry and Energy (MOTIE) of the Republic of Korea [20162000000910]
- Korea Evaluation Institute of Industrial Technology (KEIT) [20162000000910] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
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Considerable efforts have been devoted to enhancing thermoelectric performance, by employing phonon scattering from nanostructural architecture, and material design using phonon-glass and electron-crystal concepts. The nanostructural approach helps to lower thermal conductivity but has limited effect on the power factor. Here, we demonstrate selective charge Anderson localization as a route to maximize the Seebeck coefficient while simultaneously preserving high electrical conductivity and lowering the lattice thermal conductivity. We confirm the viability of interface potential modification in an n-type Bi-doped PbTe/Ag2Te nanocomposite and the resulting enhancement in thermoelectric figure-of-merit ZT. The introduction of random potentials via Ag2Te nanoparticle distribution using extrinsic phase mixing was determined using scanning tunneling spectroscopy measurements. When the Ag2Te undergoes a structural phase transition (T > 420 K) from monoclinic beta-Ag2Te to cubic alpha-Ag2Te, the band gap in the alpha-Ag2Te increases due to the p-d hybridization. This results in a decrease in the potential barrier height, which gives rise to partial delocalization of the electrons, while wave packets of the holes are still in a localized state. Using this strategic approach, we achieved an exceptionally high thermoelectric figure-of-merit in n-type PbTe materials, a ZT greater than 2.0, suitable for waste heat power generation.
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