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Boosted thermoelectric properties of molybdenum oxide thin films deposited on Si substrates
摘要： MoO2+x has novel peculiarities and complexities due to multiple valence states of 4d molybdenum, but high carrier density impedes its thermoelectric (TE) application. Recent investigation has demonstrated that the TE performance of transition metal oxide films can be greatly enhanced by activating a parallel conduction channel in the perovskite substrates through reversible incorporation of oxygen. In this work, we report the TE properties of MoO2+x thin films deposited on single crystalline Si and quartz glass substrates by magnetron sputtering. The TE power factor (PF) in the former is above 40 times bigger than that in the latter. Such a large enhancement originates mainly from the significantly enhanced Seebeck coefficient, correlated with the contribution of the Si substrate. The highest PF value 1.78 mW/(m · K2) at 700 K in this MoO2+x/Si system is comparable to the state-of-the-art in other TE thin films. Based on the preceding research, our experimental results suggest a more economic and scalable route to explore high-performance TE thin films.
关键词： thermoelectric,thin films,microstructure,Oxide materials
更新于2025-09-23 15:22:29
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Effect of substrate temperature on structural and thermoelectric properties of RF-magnetron sputtered SnSe thin film
摘要： SnSe is a potential thermoelectric material, but there are few reports about the thermoelectric properties of the film. In this work, SnSe thin films were deposited on glass substrates by RF magnetron sputtering from SnSe alloy target. The effect of substrate temperature on the structural and thermoelectric properties was investigated. It was found that the columnar grains and the surface roughness of the films increase with increasing the substrate temperature. The film deposited at 558 K exhibited a high crystalline quality and stoichiometric composition, which has a maximum power factor of 1.4 uWcm-1K-2 at 575 K. The results of this work demonstrate the importance of high substrate temperature to obtain high thermoelectric performance SnSe films.
关键词： SnSe thin film,sputtering,thermoelectric properties
更新于2025-09-23 15:22:29
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Impact of Alkyl Side Chain Length on Doping Kinetics, Thermopower and Charge Transport Properties in Highly Oriented F4TCNQ-Doped PBTTT films
摘要： Doping of polymer semiconductors such as PBTTT with acceptor molecules such as F4TCNQ is widely used to tune the charge transport and thermoelectric (TE) properties in thin films. However, the mechanism of dopant insertion in the polymer matrix, the insertion kinetics and the ultimate doping levels reached have been investigated only marginally. This contribution addresses the impact of alkyl side chain length on the doping mechanism of a series of PBTTTs with linear side chains ranging from n-octyl to n-octyldecyl. The study focuses on thin films oriented by high temperature rubbing and sequentially doped in F4TCNQ solution. Structure-property correlations are established as a function of side chain length by a combination of Transmission Electron Microscopy, polarized UV-Vis-NIR spectroscopy and charge transport / thermopower measurements. Intercalation of F4TCNQ into the layers of side chains results in the expansion of the lattice along the side chains and the contraction along the π-stacking direction for all polymers. The extent of lattice expansion decreases with increasing side chain length. UV-vis-NIR spectroscopy demonstrates integer charge transfer for all investigated PBTTTs. The doping kinetics and final doping level depend on both the side chain length and packing. Highly disordered n-octyl and crystalline n-octyldecyl side chain layers tend to hamper dopant diffusion in the side chain layers contrary to n-dodecyl side chains that can host the highest proportion of dopants. Consequently, the best TE properties are observed for C12-PBTTT films. Alignment of the polymers enhances significantly the TE performance by increasing the charge conductivity and the thermopower along the rubbing direction. Aligned films of C12-PBTTT show charge conductivities of 193 S/cm along the rubbing direction and power factors of approximately 100 μW.m-2.K-1 versus a few μW.m-2.K-1 for non-oriented films.
关键词： Thin films,Structure,Organic Thermoelectric,Conducting Polymers,Doping.
更新于2025-09-23 15:22:29
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Quantum-dot circuit-QED thermoelectric diodes and transistors
摘要： Recent breakthroughs in quantum-dot circuit-quantum-electrodynamics systems are promising both from fundamental perspectives and from the point of view of quantum photonic devices. However, understanding such setups as potential thermoelectric devices has been missing. In this paper, via the Keldysh nonequilibrium Green’s function approach, we show that cavity-coupled double quantum-dots can serve as excellent quantum thermoelectric diodes and transistors. Using an enhanced perturbation approach based on the exact polaron transformation, we find dependencies of thermoelectric transport properties on the electron-photon interaction beyond the predictions from the conventional second-order perturbation theory. In particular, strong light-matter interaction leads to pronounced rectification effects for both charge and heat, as well as thermal transistor effects in the linear transport regime, which opens up a cutting-edge frontier for quantum thermoelectric devices.
关键词： rectification,light-matter interaction,circuit-QED,diode,transistor,thermoelectric,thermal transistor,quantum-dot
更新于2025-09-23 15:22:29
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Ab-initio study of electronic, optical, thermal, and transport properties of Cr <sub/>4</sub> AlB <sub/>6</sub>
摘要： Theoretical investigation of different physical parameters of Cr4AlB6 have been done within the framework of density functional theory. Cr4AlB6 is a no band gap material. Its Cr-3d states contributes the most at the Fermi level. Thermal properties are investigated using quasi-harmonic Debye model as implemented in Gibbs code for different values of pressure and temperature. Study of transport property suggests that its electrical conductivity increases nonlinearly with increase in temperature but the relative change in its value is very low whereas its thermal conductivity increases linearly with the increase in temperature and relative increase in thermal conductivity is very high. The behavior of Cr4AlB6 is anisotropic and property is ceramic. It has potential applications in making ceramic capacitors. Its reflectivity is high in low energy region. It suggests that material can be used as coating material for far-infrared radiation. Study of the transport property suggests that because of very high value of thermal conductivity, it can be used for heat sink applications.
关键词： optical properties,first principles,electronic properties,thermal properties,thermoelectric transport properties,structural properties
更新于2025-09-23 15:22:29
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Influence of Local Heterojunction on the Thermoelectric Properties of Mo-SnSe Multilayer Films Deposited by Magnetron Sputtering
摘要： Mo-SnSe multilayer films were deposited by multi-step magnetron sputtering. The Mo-SnSe multilayer films are then annealed, and the new phases including SnSe2 and MoSe2 are observed by x-ray diffraction and Raman spectroscopy. Scanning electron microscopy reveals that the SnSe exhibits the columnar grain structure with sizes from 50–100 nm. The high-resolution transmission electron microscopy shows the SnSe2 is dispersed at the boundary of the columnar grain and the local MoSe2/SnSe heterojunction is formed in the interior of the columnar grain. The influence of Mo content on the thermoelectric properties of SnSe thin films was investigated. A maximum power factor of 0.44 μW cm?1 K?2 was obtained for a 2.6 at.% Mo-doped SnSe thin film at 576 K, which is higher than that of a SnSe thin film deposited under the same conditions.
关键词： thermoelectric properties,heterojunction,SnSe films,sputtering
更新于2025-09-23 15:22:29
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Effects of vacancy defects location on thermal conductivity of silicon nanowire: a molecular dynamics study
摘要： The improvement of thermoelectric ?gure of merit of silicon nanowire (SiNW) can be achieved by lowering its thermal conductivity. In this work, non-equilibrium molecular dynamics method was used to demonstrate that the thermal conductivity of bulk silicon crystal is drastically reduced when it is crafted as SiNW and that it can be reduced remarkably by including vacancy defects. It has been found that ‘centre vacancy defect’ contributes much more in reducing the thermal conductance than ‘surface vacancy defect’. The lowest thermal conductivity that occurs is about 52.1% of that of pristine SiNW, when 2% vacancy defect is introduced in the nanowire. The vibrational density of states analysis was performed to understand the nature of this reduction and it has been found that the various boundary scatterings of phonon signi?cantly reduce the thermal conductivity. Also, larger mass difference due to voids induces smaller thermal conductivity values. These results indicate that the inclusion of vacancy defects can enhance the thermoelectric performance of SiNWs.
关键词： molecular dynamics,silicon nanowire,thermoelectric performance,thermal conductivity,vacancy defects
更新于2025-09-23 15:21:21
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Strain-induced photo-thermoelectric terahertz detection
摘要： We report a design for terahertz (THz) detection by introducing strain to an area of a single-wall carbon nanotube (SWNT) film. The strain is achieved by bending the film around the center, and a large THz response is measured at the two photo-thermoelectric junctions created on the edges of the strained area. We attribute the THz response to an increase in the Seebeck coefficient of the SWNT film with strain, which gives rise to the photo-thermoelectric effect. The enhanced thermal performance is verified on a macroscopic scale using Non-Equilibrium Green's Function approach for SWNT networks.
关键词： photo-thermoelectric effect,strain,carbon nanotubes,Seebeck coefficient,terahertz detection
更新于2025-09-23 15:21:21
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Dye-sensitized solar cell-thermoelectric hybrid generator utilizing bipolar conduction in a unified element
摘要： The dye-sensitized solar cell-thermoelectric hybrid generator (DS-TEG), which is a hybridization of a dye-sensitized solar cell (DSSC) and a thermoelectric generator (TEG) not at the structural level but in terms of material-level unification, is presented. The Pt-coated TE element provides electrons to the iodide/triiodide electrolyte to lower the redox barrier. This promotes the reduction of triiodide, resulting in a dramatic increase in the electron recombination lifetime. The available charge density, carrier diffusion coefficient and effective diffusion length were significantly increased when utilizing both types of carriers and acceleration in an iodide/triiodide reduction reaction in the unified DS-TEG.
关键词： Dye-sensitized solar cell,synergetic effect,dye-sensitized thermoelectric hybrid generator,thermoelectric element,triiodide reduction rate
更新于2025-09-23 15:21:01
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Improving the performance and economic analysis of photovoltaic panel using copper tubular-rectangular ducted heat exchanger
摘要： This research empirically and theoretically assessed the performance of a solar photovoltaic (PV) panel in five different cooling configurations under the weather conditions of Sanandaj, Iran in September 2018. The findings indicated that, compared to the simple PV mode, the increased mean electrical efficiencies over the whole experiment were 0.27%, 0.5%, 0.72%, 0.6, and 0.88% for the PV/w-XP, PV/w-XD, PV/w-2XDP, PV/a ,and PV/b-2XDP modes, respectively. Further, the highest electrical power for the PV/w-XP, PV/w-XD, PV/w-2XDP, PV/a, and PV/b-2XDP modes increased by 6.8, 12.17, 16.83, 13.17, and 18.92%, respectively compared to the simple PV mode. The monthly electrical output energy the PV/S, PV/w-XP, PV/w-XD, PV/w-2XDP, PV/a, and PV/b-2XDP modes were 28.24 kWh/A, 29.16 kWh/A, 30.34 kWh/A, 31.81 kWh/A, 31.15 kWh/A, and 32.9 kWh/A, respectively. Then, an economic analysis was carried out for the system with two adjustment coefficients. The results showed that although the payback period with an interest rate and an adjustment coefficient of 10% was 2.72 years longer in the PV/b-2XDP than in the PV/S, the annual worth over 20 years was State USD 3.32 (SANA USD 1.07) higher in the PV/b-2XDP mode than in the PV/S mode by considering merely the electrical section. Hence, considering the outlet hot water and air, PV/b-2XDP is more economical to use.
关键词： Water tubular and channel heat exchanger,Photovoltaic panel,Payback period,Thermoelectric
更新于2025-09-23 15:21:01