Staff directory
- ORCID: 0000-0003-3358-368X
Publications
2017
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Solution-based synthesis and processing of Sn- and Bi-doped Cu3SbSe4 nanocrystals, nanomaterials and ring-shaped thermoelectric generators
Liu Y., García G., Ortega S., Cadavid D., Palacios P., Lu J., Ibáñez M., Xi L., De Roo J., López A.M., Martí-Sánchez S., Cabezas I., Mata M.D.L., Luo Z., Dun C., Dobrozhan O., Carroll D.L., Zhang W., Martins J., Kovalenko M.V., Arbiol J., Noriega G., Song J., Wahnón P., Cabot A. Journal of Materials Chemistry A; 5 (6): 2592 - 2602. 2017. 10.1039/c6ta08467b. IF: 8.867
Copper-based chalcogenides that comprise abundant, low-cost, and environmental friendly elements are excellent materials for a number of energy conversion applications, including photovoltaics, photocatalysis, and thermoelectrics (TE). In such applications, the use of solution-processed nanocrystals (NCs) to produce thin films or bulk nanomaterials has associated several potential advantages, such as high material yield and throughput, and composition control with unmatched spatial resolution and cost. Here we report on the production of Cu3SbSe4 (CASe) NCs with tuned amounts of Sn and Bi dopants. After proper ligand removal, as monitored by nuclear magnetic resonance and infrared spectroscopy, these NCs were used to produce dense CASe bulk nanomaterials for solid state TE energy conversion. By adjusting the amount of extrinsic dopants, dimensionless TE figures of merit (ZT) up to 1.26 at 673 K were reached. Such high ZT values are related to an optimized carrier concentration by Sn doping, a minimized lattice thermal conductivity due to efficient phonon scattering at point defects and grain boundaries, and to an increase of the Seebeck coefficient obtained by a modification of the electronic band structure with Bi doping. Nanomaterials were further employed to fabricate ring-shaped TE generators to be coupled to hot pipes, which provided 20 mV and 1 mW per TE element when exposed to a 160 °C temperature gradient. The simple design and good thermal contact associated with the ring geometry and the potential low cost of the material solution processing may allow the fabrication of TE generators with short payback times. © The Royal Society of Chemistry.
2015
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Tailoring thermal conductivity by engineering compositional gradients in Si
1−x Gex superlatticesFerrando-Villalba P., Lopeandía A.F., Alvarez F.X., Paul B., de Tomás C., Alonso M.I., Garriga M., Goñi A.R., Santiso J., Garcia G., Rodriguez-Viejo J. Nano Research; 8 (9): 2833 - 2841. 2015. 10.1007/s12274-015-0788-9. IF: 7.010
The transport properties of artificially engineered superlattices (SLs) can be tailored by incorporating a high density of interfaces in them. Specifically, SiGe SLs with low thermal conductivity values have great potential for thermoelectric generation and nano-cooling of Si-based devices. Here, we present a novel approach for customizing thermal transport across nanostructures by fabricating Si/Si
1−x Gex SLs with well-defined compositional gradients across the SiGe layer from x = 0 to 0.60. We demonstrate that the spatial inhomogeneity of the structure has a remarkable effect on the heat-flow propagation, reducing the thermal conductivity to ∼2.2 W·m−1·K−1, which is significantly less than the values achieved previously with non-optimized long-period SLs. This approach offers further possibilities for future applications in thermoelectricity. [Figure not available: see fulltext.] © 2015, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.