Colloidal AgSbSe<sub>2</sub> nanocrystals: surface analysis, electronic doping and processing into thermoelectric nanomaterials

Liu, Yu; Cadavid, Doris; Ibáñez, María; Roo, Jonathan De; Ortega, Silvia; Dobrozhan, Oleksandr; Kovalenko, Maksym V.; Cabot, Andreu

doi:10.1039/c6tc00893c

Cited by 32 publications

(58 citation statements)

References 45 publications

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“…However, these peaks disappeared after the sample had undergone washing treatment by a mixed solution of hydrazine hydrate and hexane, indicating that the organic groups on the NCs’ surface were removed completely. In addition, using other non-toxic inorganic salts can be considered for the ligand removal in order to implement this material in TE devices in future work, such as sodium salts [47] and ammonium salts [18]. …”

Section: Resultsmentioning

confidence: 99%

Colloidal Synthesis and Thermoelectric Properties of CuFeSe2 Nanocrystals

et al. 2017

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Copper-based chalcogenides that contain abundant, low-cost and environmentally-friendly elements, are excellent materials for numerous energy conversion applications, such as photocatalysis, photovoltaics, photoelectricity and thermoelectrics (TE). Here, we present a high-yield and upscalable colloidal synthesis route for the production of monodisperse ternary I-III-VI2 chalcogenides nanocrystals (NCs), particularly stannite CuFeSe2, with uniform shape and narrow size distributions by using selenium powder as the anion precursor and CuCl2·2H2O and FeCl3 as the cationic precursors. The composition, the state of valence, size and morphology of the CuFeSe2 materials were examined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM), respectively. Furthermore, the TE properties characterization of these dense nanomaterials compacted from monodisperse CuFeSe2 NCs by hot press at 623 K were preliminarily studied after ligand removal by means of hydrazine and hexane solution. The TE performances of the sintered CuFeSe2 pellets were characterized in the temperature range from room temperature to 653 K. Finally, the dimensionless TE figure of merit (ZT) of this Earth-abundant and intrinsic p-type CuFeSe2 NCs is significantly increased to 0.22 at 653 K in this work, which is demonstrated to show a promising TE materialand makes it a possible p-type candidate for medium-temperature TE applications.

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Section: Resultsmentioning

confidence: 99%

Colloidal Synthesis and Thermoelectric Properties of CuFeSe2 Nanocrystals

et al. 2017

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“…74 Furthermore, as the scalability is also a crucial point for the suitability of the technique for the large-scale production, in different occasions it has been proved its high throughput together with the development of a continuous production method or flow reactor. [75][76][77] Figure 0.11 Representative transmission and scanning microscope micrographs of some of the bottom-up solution-processed TE NPs produced by the PhD candidate.…”

Section: Production Of Bulk Te Materialsmentioning

confidence: 99%

Bottom-up engineering of thermoelectric nanomaterials and devices from solution-processed nanoparticle building blocks

et al. 2017

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The conversion of thermal energy to electricity and vice versa by means of solid state thermoelectric devices is extremely appealing. However, its cost-effectiveness is seriously hampered by the relatively high production cost and low efficiency of current thermoelectric materials and devices. To overcome present challenges and enable a successful deployment of thermoelectric systems in their wide application range, materials with significantly improved performance need to be developed. Nanostructuration can help in several ways to reach the very particular group of properties required to achieve high thermoelectric performances. Nanodomains inserted within a crystalline matrix can provide large charge carrier concentrations without strongly influencing their mobility, thus allowing to reach very high electrical conductivities. Nanostructured materials contain numerous grain boundaries that efficiently scatter mid- and long-wavelength phonons thus reducing the thermal conductivity. Furthermore, nanocrystalline domains can enhance the Seebeck coefficient by modifying the density of states and/or providing type- and energy-dependent charge carrier scattering. All these advantages can only be reached when engineering a complex type of material, nanocomposites, with exquisite control over structural and chemical parameters at multiple length scales. Since current conventional nanomaterial production technologies lack such level of control, alternative strategies need to be developed and adjusted to the specifics of the field. A particularly suitable approach to produce nanocomposites with unique level of control over their structural and compositional parameters is their bottom-up engineering from solution-processed nanoparticles. In this work, we review the state-of-the-art of this technology applied to the thermoelectric field, including the synthesis of nanoparticles of suitable materials with precisely engineered composition and surface chemistry, their combination and consolidation into nanostructured materials, the strategies to electronically dope such materials and the attempts to fabricate thermoelectric devices using nanoparticle-based nanopowders and inks.

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“…11,12 While numerous approaches to produce nanomaterials exist, nanocrystal (NC)-based bottomup strategies allow an unparalleled combination of delicate control over material parameters with high production throughputs. 5,[13][14][15][16][17] In this regard, NC-based approaches offer clear advantages over currently more conventional nanomaterial fabrication methods, which lack sufficient control over material parameters, e.g. ball milling, 18 and/or are too costly for an eventual large volume industrial manufacturing of cost-effective TE modules, e.g.…”

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High Thermoelectric Performance in Crystallographically Textured n-Type Bi₂Te_3–xSe_x Produced from Asymmetric Colloidal Nanocrystals

et al. 2018

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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.

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Colloidal AgSbSe₂ nanocrystals: surface analysis, electronic doping and processing into thermoelectric nanomaterials

Cited by 32 publications

References 45 publications

Colloidal Synthesis and Thermoelectric Properties of CuFeSe2 Nanocrystals

Colloidal Synthesis and Thermoelectric Properties of CuFeSe2 Nanocrystals

Bottom-up engineering of thermoelectric nanomaterials and devices from solution-processed nanoparticle building blocks

High Thermoelectric Performance in Crystallographically Textured n-Type Bi₂Te_3–xSe_x Produced from Asymmetric Colloidal Nanocrystals

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Colloidal AgSbSe2 nanocrystals: surface analysis, electronic doping and processing into thermoelectric nanomaterials

Cited by 32 publications

References 45 publications

Colloidal Synthesis and Thermoelectric Properties of CuFeSe2 Nanocrystals

Colloidal Synthesis and Thermoelectric Properties of CuFeSe2 Nanocrystals

Bottom-up engineering of thermoelectric nanomaterials and devices from solution-processed nanoparticle building blocks

High Thermoelectric Performance in Crystallographically Textured n-Type Bi2Te3–xSex Produced from Asymmetric Colloidal Nanocrystals

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Colloidal AgSbSe₂ nanocrystals: surface analysis, electronic doping and processing into thermoelectric nanomaterials

High Thermoelectric Performance in Crystallographically Textured n-Type Bi₂Te_3–xSe_x Produced from Asymmetric Colloidal Nanocrystals