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Nanostructuring of dense SnO2 ceramics by Spark Plasma Sintering
摘要： The spark plasma sintering (SPS) behaviour of pure SnO2 has been studied. Two different SnO2 powders have been studied: a commercial 50–200 nm one and 4–6 nm nanoparticles obtained by precipitation. It has demonstrated that it is not possible to keep pure SnO2 above 1223 K by SPS. Indeed, at 1248 K, SnO appears whereas at higher temperatures, samples are composed by SnO2 and metal Sn. Three different cycles have been developed that allow achieving high densities (≥94%). The study of the grain size shows that when the density increases the grain size increases to reach 60–70 nm for the high density samples. Therefore, SPS can be successfully used to produce dense nanostructured SnO2 ceramics without any sintering agent. Nanostructuring is very efficient to lower thermal conductivity as values as low as 6.59 and 3.99 W m?1.K?1 at 373 and 1000 K respectively, are measured in SPS nanostructured ceramics. Moreover, the transport properties of the dense ceramics are the best reported for undoped SnO2.
关键词： Spark plasma sintering,Tin oxide,Thermal conductivity,Thermoelectric,Nanostructuring
更新于2025-09-19 17:15:36
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Size effect-enhanced thermoelectric properties of nanoscale Cu2-xSe
摘要： As a promising thermoelectric material, copper selenides have attracted the interest of researchers owing to their low cost, abundance in earth, environmental friendliness, and low thermal conductivity. In this study, copper selenide (Cu2-xSe) powders with controllable sizes from nanoscale to mesoscale were obtained by a facile one-pot solvothermal method. After treatment with spark plasma sintering, the nanoscale Cu2-xSe pellets exhibited excellent thermoelectric properties such as sharply reduced thermal conductivity and enhanced Seebeck coefficient as well as a suppressed electrical conductivity. The figure of merit (ZT) of the nanoscale Cu2-xSe reached up to ~1.51 at 873 K, which is about 2.67 times higher than that of the meso-Cu2-xSe. This study confirms that thermoelectric properties can be enhanced by the size effect.
关键词： size effect,solvothermal method,thermoelectric property,Copper selenide,nanoscale
更新于2025-09-19 17:15:36
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Doping of Donor-Acceptor Polymers with Long Side Chains via Solution Mixing for Advancing Thermoelectric Properties
摘要： One-step doping of conjugated polymers by solution mixing is typically performed instead of sequential doping because of its simplicity. However, doped polymer solutions often exhibit poor solubility, and the presence of dopants in the produced films can disturb the molecular ordering of polymer structures. In this work, effective pairs of two donor-acceptor (D-A) type polymers and a molecular dopant characterized by high solution stability and good thermoelectric properties of the prepared thin films have been reported. The presence of long side chains in the polymer structures preserves their original solubilities and crystallinity in the solution and thin-film states, respectively, even at large amounts of added dopant (up to 38 mol%). Furthermore, the relatively shallow levels of the highest occupied molecular orbitals of the selected D-A polymers enable efficient charge transfer from the dopant species. Owing to their good charge transport properties, the doped D-A polymers exhibit outstanding thermoelectric properties with a maximum power factor of 31.5 μW m?1 K?2, which is more than an order of magnitude higher than those of the control samples prepared from donor-only poly(3-hexylthiophene).
关键词： molecular doping,donor-acceptor polymers,power factors,long side chains,solution mixing,organic thermoelectric materials
更新于2025-09-19 17:15:36
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Synthesis, characterization and thermoelectric performance of Mg2(Si,Sn,Ge) materials using Si-kerf waste from photovoltaic technology
摘要： The recycling acquisition of silicon waste from photovoltaic industry has gained an increasing attention nowadays, since more than 50% of high purity material ends up as kerf during the wafer cutting process. Currently, different Si-based applications are being exploited in terms of using such Si kerf, in order to lower cost and significantly increase environmental impact. Thermoelectric devices can efficiently contribute towards this recycling approach, via the preparation of highly efficient silicides for power generation. In this work, Bi doped Mg2(Si,Sn,Ge) materials were prepared using Si-kerf originated from photovoltaic (PV) cutting wastes. Different Bi concentrations were studied in terms of thermoelectric properties and performance and a high figure-of-merit of 1.1. was achieved at 800K. In addition, a thorough structural and mechanical property characterization, such as morphology, phase identification, hardness and indentation modulus has been conducted. These results, which were evaluated and compared to materials prepared with pure Si (>99.9%), are presented for the first time for Mg2(Si,Sn,Ge) materials.
关键词： magnesium silicides,thermoelectric figure of merit,mechanical/structural properties,multiphase,silicon,recycling
更新于2025-09-19 17:13:59
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Solar energy harvesting potential of a photovoltaic-thermoelectric cooling and power generation system: Bidirectional modeling and performance optimization
摘要： In the present work, a comprehensive thermodynamic and exergoeconomic comparison between concentrated photovoltaic-thermoelectric cooling (CPV-TEC) and concentrated photovoltaic-thermoelectric generation (CPV-TEG) systems was introduced and explored, aiming to actively investigate the energy harvesting potential of the photoelectric-thermoelectric cooling and power generation processes. Transitional characteristics of thermoelectric conversion in concentrated photovoltaic-thermoelectric hybrid (CPV-TEH) system have been outlined through multiple evaluation indicators, including output electricity, cell temperature, thermodynamic efficiency, exergy destruction and unit exergy cost under various decision parameters. Furthermore, operating mode and conversion conditions of thermoelectric device in CPV-TEH system have been sensitively identified to obtain the dual action mechanism of cooling and power generation sequentially. Theoretical models have been compared and validated well with former published results. Results indicate that the operating mode of thermoelectric device could be fully converted from TEG to TEC when the operating current is around 0.27 A; the minimum unit exergy costs are respectively found to be 0.263 $/kwh, 0.148 $/kwh and 0.113 $/kwh for CPV-TEG system and 0.266 $/kwh, 0.152 $/kwh and 0.118 $/kwh for CPV-TEC system at CG = 1, 2, and 3 kW/m2. Present research may be helpful for the design and optimization of the CPV-TEH system to harvest the thermal and electric energy from the sunlight, thus enhancing its energy conversion efficiency.
关键词： Photovoltaic-thermoelectric system,Refrigeration and power generation,Thermodynamic and exergoeconomic comparisons,Dual action mechanism
更新于2025-09-19 17:13:59
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Performance of hybrid energy devices consisting of photovoltaic cells and thermoelectric generators
摘要： The aim of our study on hybrid energy devices (HEDs) is to find out the prerequisites for enhancing the performance of the HEDs using solar energy. In this work, first of all, the performance of the HEDs composed of photovoltaic cells (PVCs) and thermoelectric generators (TEGs) is analyzed, and then the contribution of three different interfaces between the PVC and TEG components to HED performance is assessed under solar irradiance from 200 to 1000 W/m2. The significant result of the analysis emphasizes that the performance of HEDs is enhanced when short-circuit current in HEDs is comparable with the PVCs and the thermoelectric voltage generated by the TEG is large. Furthermore, interfaces with high solar-energy-absorption efficiencies and high thermal conductivity cause TEGs to generate large thermoelectric voltages. Thus, the design of the interfaces plays an important role in enhancing HED performance.
关键词： Hybrid energy device,Photovoltaic,Thermoelectric,Interface layer,Current matching
更新于2025-09-19 17:13:59
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Spectral absorption control of femtosecond laser-treated metals and application in solar-thermal devices
摘要： Direct femtosecond (fs) laser processing is a maskless fabrication technique that can effectively modify the optical, electrical, mechanical, and tribological properties of materials for a wide range of potential applications. However, the eventual implementation of fs-laser-treated surfaces in actual devices remains challenging because it is difficult to precisely control the surface properties. Previous studies of the morphological control of fs-laser-processed surfaces mostly focused on enhancing the uniformity of periodic microstructures. Here, guided by the plasmon hybridisation model, we control the morphology of surface nanostructures to obtain more control over spectral light absorption. We experimentally demonstrate spectral control of a variety of metals [copper (Cu), aluminium (Al), steel and tungsten (W)], resulting in the creation of broadband light absorbers and selective solar absorbers (SSAs). For the first time, we demonstrate that fs-laser-produced surfaces can be used as high-temperature SSAs. We show that a tungsten selective solar absorber (W-SSA) exhibits excellent performance as a high-temperature solar receiver. When integrated into a solar thermoelectric generation (TEG) device, W-SSA provides a 130% increase in solar TEG efficiency compared to untreated W, which is commonly used as an intrinsic selective light absorber.
关键词： spectral light absorption,plasmon hybridisation model,selective solar absorbers,solar thermoelectric generation,broadband light absorbers,femtosecond laser processing
更新于2025-09-19 17:13:59
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Optimization and performance analysis of a solar concentrated photovoltaic-thermoelectric (CPV-TE) hybrid system
摘要： This work presents, for the first time, a statistical model to forecast the electrical efficiency of concentrated photovoltaic-thermoelectric system (CPV-TE). The main objective of this work is to analyze the impact of the input factors (product of solar radiation and optical concentration, external load resistance, leg height of TE and ambient temperature) most affecting the electrical efficiency of CPV-TE system. An innovative and integrated approach based on a multi-physics numerical model coupling radiative, conductive and convective heat transfers Seebeck and photoelectrical conversion physical phenomena inside the CPV-TE collector and a response surface methodology (RSM) model was developed. COMSOL 5.4 Multiphysics software is used to perform the three-dimensional numerical study based on finite element method. Furthermore, results from the numerical model is then analysed using the statistical tool, response surface methodology. The analysis of variance (ANOVA) is conducted to develop the quadratic regression model and examine the statistical significance of each input factor. The results reveal that the obtained determination coefficient for electrical efficiency is 0.9945. An excellent fitting is achieved between forecast values obtained from the statistical model and the numerical data provided by the three-dimensional numerical model. The influence of the parameters in order of importance on the electrical efficiency are respectively: product of solar radiation and optical concentration, the height legs of TE, external electrical resistance load, and ambient temperature. A simple polynomial statistical model is created in this work to predict and maximize the electrical efficiency from the solar CPV-TE system based on the four investigated input parameters. The maximum electrical efficiency of the proposed CPVTE (17.448%) is obtained for optimum operating parameters at 229.698 W/m2 value of product of solar radiation and optical concentration, 303.353 K value of ambient temperature, 2.681Ω value of resistance electrical load and at 3.083 mm value of height of TE module.
关键词： Concentrated photovoltaic-thermoelectric system (CPV-TE),Electrical efficiency enhancement,Response surface methodology (RSM)
更新于2025-09-19 17:13:59
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EXPRESS: Evaluation of a Thermoelectric Cooler as a Sample Pre-Treatment Method for Laser Induced Breakdown Spectroscopy (LIBS) Analysis of Liquid Samples
摘要： In this study, the performance of a thermoelectric cooler (TEC) as a simple and easy-to-assemble freezing instrument has been evaluated. Experiments were carried out using samples with different viscosity ranging from 44.07 to 16,965.80 mPas. The analysis on sodium component of the samples by direct laser irradiation of frozen samples showed emission enhancement and higher signal-to-noise ratio (SNR) compared to that of liquids. This work also focused on using chemometrics methods such as principal component analysis (PCA) to compare the PC score separation and clustering pattern between frozen and liquid samples. The PCA was constructed by dividing the samples into two different categories: (i) type (paste, cream, gel and oil); and (ii) viscosity (more than and less than 10000 mPas). The frozen samples showed a more established separation and clustering compared to that acquired from the liquid samples. However, poorer clustering pattern of some frozen samples could be due to the heat transfer during laser–sample interaction inducing surface melting and splashing. The average LIBS spectra were taken at as many different surface areas as possible to ensure the sample surface always maintain similar freezing temperature. This work showed that the TEC pre-treatment method had improved the LIBS measurement of the liquid samples.
关键词： viscosity,liquid sample,LIBS,Laser induced breakdown spectroscopy,thermoelectric cooler
更新于2025-09-19 17:13:59
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Defects controlled doping and electrical transport in TiS <sub/>2</sub> single crystals
摘要： TiS2 has been intensively studied as an electrode material and a thermoelectric material for energy storage and conversion applications due to its high electrical conductivity. Understanding the influence of defects on electrical transport is of importance not only to resolve the long-standing question concerning the nature of TiS2, but also for the rational design of TiS2 based devices for energy scavenging applications. In this study, we integrate photoemission spectroscopy, Raman spectroscopy, and electrical transport measurements to determine the chemical compositions dominated by defects and their influence on the doping and electrical properties. Our results demonstrate that TiS2 is a heavily self-doped semiconductor with the Fermi level close to the conduction band, which serves as the conclusive experimental evidence regarding the semiconducting nature of TiS2. The doping effect is sensitive to the (subtle) changes in the chemical composition. The electron donation from the Ti interstitials (Tii) to the TiS2 host explains the high carrier concentration. The Ti Frenkel pair (TiF) acting as the acceptor is responsible for the decrease in the electron carrier concentration and electrical conductivity. High conductivity maintains upon partial oxidization, indicating the oxidization-tolerance in terms of the electronic structure. Our results provide valuable insight into the evolution of electronic properties modulated by defects that reveal unambiguously the self-doped semiconducting nature of TiS2 and chemical- and environment-tolerance of TiS2 as an advanced energy scavenging material.
关键词： TiS2,doping,defects,electrical transport,energy storage,energy conversion,photoemission spectroscopy,thermoelectric material,Raman spectroscopy
更新于2025-09-19 17:13:59