期刊
CHEMICAL ENGINEERING JOURNAL
卷 418, 期 -, 页码 -出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2021.129374
关键词
Bi2Te3; Nanocomposites; Energy filtering effect; Cu2-xTe; Thermoelectricity
资金
- European Regional Development Funds
- Generalitat de Catalunya [2017 SGR 327, 2017SGR1246]
- China Scholarship Council
- IST Austria
- European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant [754411]
- Spanish MINECO project [ENE201785087C3]
- Severo Ochoa program from the Spanish MINECO [SEV-2017-0706]
- CERCA Program/Generalitat de Catalunya
In this study, a low temperature solution-based method was used to prepare Bi2Te3-Cu2-xTe nanocomposites with improved thermoelectric performance, showing nearly a threefold increase in power factor compared to pure Bi2Te3 nanomaterials. The introduction of Cu2-xTe nanoparticles enhanced the Seebeck coefficient and electrical conductivity, leading to a 250% improvement in the thermoelectric figure of merit of Bi2Te3.
The high processing cost, poor mechanical properties and moderate performance of Bi2Te3-based alloys used in thermoelectric devices limit the cost-effectiveness of this energy conversion technology. Towards solving these current challenges, in the present work, we detail a low temperature solution-based approach to produce Bi2Te3-Cu2-xTe nanocomposites with improved thermoelectric performance. Our approach consists in combining proper ratios of colloidal nanoparticles and to consolidate the resulting mixture into nanocomposites using a hot press. The transport properties of the nanocomposites are characterized and compared with those of pure Bi2Te3 nanomaterials obtained following the same procedure. In contrast with most previous works, the presence of Cu2-xTe nanodomains does not result in a significant reduction of the lattice thermal conductivity of the reference Bi2Te3 nanomaterial, which is already very low. However, the introduction of Cu2-xTe yields a nearly threefold increase of the power factor associated to a simultaneous increase of the Seebeck coefficient and electrical conductivity at temperatures above 400 K. Taking into account the band alignment of the two materials, we rationalize this increase by considering that Cu2-xTe nanostructures, with a relatively low electron affinity, are able to inject electrons into Bi2Te3, enhancing in this way its electrical conductivity. The simultaneous increase of the Seebeck coefficient is related to the energy filtering of charge carriers at energy barriers within Bi2Te3 domains associated with the accumulation of electrons in regions nearby a Cu2-xTe/Bi2Te3 heterojunction. Overall, with the incorporation of a proper amount of Cu2-xTe nanoparticles, we demonstrate a 250% improvement of the thermoelectric figure of merit of Bi2Te3.
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