Thermoelectric properties of SnSe nanowires with different diameters (original) (raw)
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An Overview of the Strategies for Tin Selenide Advancement in Thermoelectric Application
Micromachines
Chalcogenide, tin selenide-based thermoelectric (TE) materials are Earth-abundant, non-toxic, and are proven to be highly stable intrinsically with ultralow thermal conductivity. This work presented an updated review regarding the extraordinary performance of tin selenide in TE applications, focusing on the crystal structures and their commonly used fabrication methods. Besides, various optimization strategies were recorded to improve the performance of tin selenide as a mid-temperature TE material. The analyses and reviews over the methodologies showed a noticeable improvement in the electrical conductivity and Seebeck coefficient, with a noticeable decrement in the thermal conductivity, thereby enhancing the tin selenide figure of merit value. The applications of SnSe in the TE fields such as microgenerators, and flexible and wearable devices are also discussed. In the future, research in low-dimensional TE materials focusing on nanostructures and nanocomposites can be conducted w...
2018
Thermoelectric technology converts thermal energy to electricity. Many studies were conducted on thermoelectric materials such as Bismuth Telluride and Lead Telluride. And the goal was to achieve an average ZT >2 which is required for waste heat recovery applications. Recently Tin Selenide (SnSe) showed a promising performance with a ZT of nearly 2.6 at 923 K for its single crystal structure at the b-axis. However, single crystal SnSe is very fragile and the production of single crystal SnSe structure is a complicated and costly process. Therefore, great interest was given to polycrystalline SnSe. In this work, the thermoelectric performance of polycrystalline SnSe was enhanced through nanostructuring and nano-composting with graphene via a cost-effective methodology. Nanocrystalline SnSe composites were successfully prepared by high energy ball milling and SPS techniques, and the structural characterization by X-ray Diffraction and Transmission Electron Microscopy revealed that the average grain size of both pristine SnSe and SnSe with Graphene was approximately (~ 10 nm). The mechanical properties were evaluated and showed an enhancement with high hardness values. The nanostructuring contributed in the enhancement of Seebeck coefficient and the highest reported value so far was obtained for pristine SnSe with 1032 μV/K at 873K. A significant
Controlled Morphology and Its Effects on the Thermoelectric Properties of SnSe2 Thin Films
Crystals, 2021
In the last few years, the thermoelectric properties of tin selenide (SnSe) have been explored in much detail due to its high efficiency and green nature, being free of Te and Pb. In the same chalcogenide family, SnSe2 is also a layered structured material, but its thermoelectric potential has not been widely explored experimentally. Since SnSe2 has the layered structure, its electrical transport properties may strongly be affected by its microstructure and morphology. Here, we report the effect of reaction time on the structure, phase, and morphology of the SnSe2 during solvothermal synthesis process. We have studied four SnSe2 samples with different reaction times. The sample obtained after 16 h of reaction time was named as M1, for 20 h M2, similarly for 24 h was M3 and for 48 hours’ time, the sample was named as M4. We investigated its thermoelectric properties and found that phase purity and morphology can affect the thermoelectric performance of the synthesized samples. The pe...
Thermoelectric properties of SnSe nanoribbons: a theoretical aspect
Materials Research Express, 2016
Bulk SnSe is reported to be an excellent thermoelectric material at high temperatures. We now present the results on thermoelectric properties of nanoribbons of SnSe of variable widths obtained using density functional theory coupled with semi-classical Boltzmann theory. The calculated results find armchair nanoribbons of width 47 Å to be semiconducting and zigzag nanoribbons of width 52 Å to be metallic. A relatively high Seebeck coefficient (≈1720 μV K −1) and low thermal conductivity was calculated for the armchair nanoribbon of 6 Å width, while a large relaxation time and small effective mass was obtained for the armchair nanoribbon of 47 Å width. The calculated results suggest that patterning SnSe into nanoribbons may provide thermoelectric performance that is similar to the monolayer and low-temperature bulk phases of SnSe.
2020
Tin selenide (SnSe) has attracted much attention in the thermoelectric community since the discovery of the record ZT of 2.6 in single crystal tin selenide in 2014. There have been many reports since of the thermoelectric characterization of SnSe synthesized or manufactured by several methods, but so far none of these have concerned the electrodeposition of SnSe. In this work, stoichiometric SnSe was successfully electrodeposited at -0.50 V vs. SCE as shown by EDX, XPS, UPS and XRD. The full ZT of the electrodeposits were then fully measured. This was done by both a delamination technique to measure the Seebeck coefficient and electrical conductivity which showed a peak power factor of 4.2 and 5.8 µW m-1 K-2 for the as deposited and heat-treated films respectively. A novel modified transient 3-ω method was used to measure the thermal conductivity of the deposited films on the deposition substrate. This revealed the thermal conductivity to be similar to the ultralow thermal conductiv...
Tin Diselenide Molecular Precursor for Solution‐Processable Thermoelectric Materials
Angewandte Chemie International Edition, 2018
In the present work, we detail a fast and simple solutionbased method to synthesize hexagonal nanoplates (NPLs) and their use to produce crystallographically textured SnSe2 nanomaterials. We also demonstrate that the same strategy can be used to produce orthorhombic SnSe nanostructures and nanomaterials. NPLs are grown though a screw dislocation-driven mechanism with additional detachment of the growing layers, resulting in flower-like structures. SnSe2 bulk nanomaterials with a significant crystallographic texture and obtained from the hot pressing of the SnSe2 NPLs display highly anisotropic charge and heat transport properties. The overall thermoelectric (TE) figures of merit of thus obtained SnSe2 nanomaterials is limited by their relatively low electrical conductivity. To improve this parameter, SnSe2 NPLs are blended with metal nanoparticles. The electrical conductivities of the blends are significantly improved with respect to bare SnSe2 NPLs and a threefold increase in the TE figure of merit is obtained, reaching unprecedented values up to ZT = 0.65 for this material.
Determining factors of thermoelectric properties of semiconductor nanowires
Nanoscale Research Letters, 2011
It is widely accepted that low dimensionality of semiconductor heterostructures and nanostructures can significantly improve their thermoelectric efficiency. However, what is less well understood is the precise role of electronic and lattice transport coefficients in the improvement. We differentiate and analyze the electronic and lattice contributions to the enhancement by using a nearly parameter-free theory of the thermoelectric properties of semiconductor nanowires. By combining molecular dynamics, density functional theory, and Boltzmann transport theory methods, we provide a complete picture for the competing factors of thermoelectric figure of merit. As an example, we study the thermoelectric properties of ZnO and Si nanowires. We find that the figure of merit can be increased as much as 30 times in 8-Å-diameter ZnO nanowires and 20 times in 12-Å-diameter Si nanowires, compared with the bulk. Decoupling of thermoelectric contributions reveals that the reduction of lattice thermal conductivity is the predominant factor in the improvement of thermoelectric properties in nanowires. While the lattice contribution to the efficiency enhancement consistently becomes larger with decreasing size of nanowires, the electronic contribution is relatively small in ZnO and disadvantageous in Si.
Tin Selenide Molecular Precursor for the Solution Processing of Thermoelectric Materials and Devices
In the present work, we report a solution-based strategy to produce crystallographically textured SnSe bulk nanomaterials and printed layers with optimized thermoelectric performance in the direction normal to the substrate. Our strategy is based on the formulation of a molecular ink that can be continuously decomposed to produce a SnSe powder or printed into predefined patterns. The ink formulation and decomposition conditions are optimized to produce pure phase SnSe. The printed layer and the bulk material obtained after hot press display a clear preferential orientation of the crystallographic domains, with the a crystal direction parallel to the pressure axis and normal to the substrate. Such textured nanomaterials present highly anisotropic properties, with best thermoelectric performance in plane, i.e. in the directions parallel to the substrate, which coincide with the crystallographic bc plane of SnSe. This is an unfortunate characteristic because thermoelectric devices are designed to create/harvest temperature gradients in the direction normal to the substrate. We demonstrate that this limitation can be overcome with the introduction of small amounts of tellurium in the precursor ink. The presence of tellurium allows reducing the band gap, increase both charge carrier concentration and mobility, especially cross plane, with a minimal decrease of the Seebeck coefficient. These effects translate into record out of plane ZT values at 800 K.