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| Pàgina inicial > Articles > Articles publicats > High Thermoelectric Performance in Crystallographically Textured n-Type Bi2Te3- xSex Produced from Asymmetric Colloidal Nanocrystals |
(Institut de Recerca en Energia de Catalunya) (Institut de Recerca en Energia de Catalunya) (Hong Kong University of Science and Technology. Department of Chemical and Biological Engineering) (Empa-Swiss Federal Laboratories for Materials Science and Technology) (Institut de Recerca en Energia de Catalunya) (Institut Català de Nanociència i Nanotecnologia) (Institut Català de Nanociència i Nanotecnologia) (Institut Català de Nanociència i Nanotecnologia) (ETH Zürich. Department of Chemistry and Applied Biosciences) (Universidad Nacional de Colombia. Departamento de Física) (Institut de Recerca en Energia de Catalunya)
| Data: | 2018 |
| Resum: | In the present work, we demonstrate crystallographically textured n-type BiTeSe nanomaterials with exceptional thermoelectric figures of merit produced by consolidating disk-shaped BiTeSe colloidal nanocrystals (NCs). Crystallographic texture was achieved by hot pressing the asymmetric NCs in the presence of an excess of tellurium. During the hot press, tellurium acted both as lubricant to facilitate the rotation of NCs lying close to normal to the pressure axis and as solvent to dissolve the NCs approximately aligned with the pressing direction, which afterward recrystallize with a preferential orientation. NC-based BiTeSe nanomaterials showed very high electrical conductivities associated with large charge carrier concentrations, n. We hypothesize that such large n resulted from the presence of an excess of tellurium during processing, which introduced a high density of donor Te antisites. Additionally, the presence in between grains of traces of elemental Te, a narrow band gap semiconductor with a work function well below BiTeSe, might further contribute to increase n through spillover of electrons, while at the same time blocking phonon propagation and hole transport through the nanomaterial. NC-based BiTeSe nanomaterials were characterized by very low thermal conductivities in the pressing direction, which resulted in ZT values up to 1. 31 at 438 K in this direction. This corresponds to a ca. 40% ZT enhancement from commercial ingots. Additionally, high ZT values were extended over wider temperature ranges due to reduced bipolar contribution to the Seebeck coefficient and the thermal conductivity. Average ZT values up to 1. 15 over a wide temperature range, 320 to 500 K, were measured, which corresponds to a ca. 50% increase over commercial materials in the same temperature range. Contrary to most previous works, highest ZT values were obtained in the pressing direction, corresponding to the c crystallographic axis, due to the predominance of the thermal conductivity reduction over the electrical conductivity difference when comparing the two crystal directions. |
| Ajuts: | European Commission 665919 European Commission 306733 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-327 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1246 Ministerio de Economía y Competitividad SEV-2013-0295 Ministerio de Economía y Competitividad ENE2017-85087-C3 |
| Drets: | Tots els drets reservats.  |
| Llengua: | Anglès |
| Document: | Article ; recerca ; Versió acceptada per publicar |
| Matèria: | Nanocrystal ; Colloid ; Crystallographic texture ; Liquid-phase sintering ; Thermoelectricity |
| Publicat a: | ACS nano, Vol. 12, Issue 7 (July 2018) , p. 7174-7184, ISSN 1936-086X |
32 p, 2.0 MB |
