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Structural and thermoelectric properties of copper sulphide powders
摘要： Over the past few years, Cu-based materials have been intensively studied focusing on their structural and thermoelectric properties. In this work, copper sulphide powders were synthesized by the sol-gel method. The chemical composition and the morphological properties of the obtained samples were analyzed by X-ray diffraction, differential thermal analysis, and scanning electron microscopy. It is shown that the decomposition from one phase to another can be obtained by annealing. The electrical resistivity and the crystallite size were found to be strongly affected by the phase transition. Thermoelectric analyses showed that the digenite phase exhibits the highest power factor at room temperature. The Seebeck coefficient of the compound Cu1.8S shows a pronounced peak at the γ–β transition temperature. This behavior was statistically explained in terms of a dramatic increase in the disorder in the atoms-carriers ensemble.
关键词： thermoelectricity,copper sulphide,annealing temperature,phase transition
更新于2025-09-23 15:22:29
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Photoelectricity and thermoelectricity in organic chlorophyll phototransistors
摘要： As one kind of organic semiconductor materials, Chlorophyll has been attracted great attention with remarkable optical properties. Here, we demonstrate photoresponse and thermoelectric current in the biological Chlorophyll A field effect phototransistors (FEpTs). Meanwhile, it exhibits excellent performances including high responsivity (5×1013 A/W) and relatively fast response time (rise time ~ 20.3 s, fall time ~ 28.2 s) under illumination by 405 nm. Utilizing thermionic emission theory and typical Arrehenius plot, Schottky barrier B is found to be 76.6 meV. The biological phototransistor via low-cost, simple, and scalable fabrication processes opens up new opportunities to realize flexible, transparent organic electronic, and biologically optoelectronic devices.
关键词： Schottky junction,photoelectricity and thermoelectricity,Chlorophyll,Organic phototransistor
更新于2025-09-23 15:21:21
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Tweaking the physics of interfaces between monolayers of buckled cadmium sulfide for a superhigh piezoelectricity, excitonic solar cell efficiency and thermoelectricity
摘要： Interfaces of heterostructures are routinely studied for different applications. Interestingly, monolayers of the same material when interfaced in an unconventional manner can bring about novel properties. For instance, CdS monolayers, stacked in a particular order, are found to show unprecedented potential in the conversion of nanomechanical energy, solar energy and waste heat into electricity, which has been systematically investigated in this work, using DFT based approaches. Moreover, stable ultrathin structures showing strong capabilities for all kinds of energy conversion are scarce. The emergence of a very high out-of-plane piezoelectricity, |d33| ~ 56 pm/V, induced by the inversion symmetry broken in the buckled structure helps to supersede the previously reported bulk wurzite GaN, AlN and Janus multilayer structures of Mo and W based dichalcogenides. The piezoelectric coefficients have been found to be largely dependent on the relative stacking between the two layers. CdS bilayer is a direct band gap semiconductor with its band edges straddling the water redox potential, thereby making it thermodynamically favorable for photocatalytic applications. Strain engineering facilitates its transition from type-I to type-II semiconductor in CdS bilayer stacked over monolayer boron phosphide, and the theoretically calculated power conversion efficiency (PCE) in the 2D excitonic solar cell exceeds 27% for a fill factor of 0.8, which is much higher than that in ZnO/CdS/CuInGaSe solar cell (20% efficiency). Thermoelectric properties have been investigated using semi classical Boltzmann transport equations for electrons and phonons within the constant relaxation time approximation coupled to deformation potential theory, which reveal ultralow thermal conductivity (~ 0.78 Wm-1K-1) at room temperature due to the presence of heavy element Cd, strong anharmonicity (high mode Gruneisen parameter at long wavelength, phonon lifetime < 5 ps), low phonon group velocity (4 km/s) and low Debye temperature (260 K). Such a low thermal conductivity is lower than that of dumbbell silicene (2.86 Wm-1K-1), SnS2 (6.41 Wm-1K-1) and SnSe2 (3.82 Wm-1K-1), SnP3 (4.97 Wm-1K-1). CdS bilayer shows a thermoelectric figure of merit (ZT) ~ 0.8 for p-type and ~ 0.7 for n-type doping at room temperature. Its ultrahigh carrier mobility (μe ~2270 cm2V-1s-1) is higher than that of single layer MoS2 and comparable to that in InSe. The versatile properties of CdS bilayer together with its all-round stability supported by ab initio molecular dynamics simulation, phonon dispersion and satisfaction of Born-Huang stability criteria highlight its outstanding potential for applications in device fabrication and applications in next generation nanoelectronics and energy harvesting.
关键词： Power conversion efficiency,Excitonic solar cell,Piezoelectricity,Photocatalysis,Solar energy,Semiconductor,Thermoelectricity,Carrier mobility
更新于2025-09-23 15:21:01
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Tin Diselenide Molecular Precursor for Solution-Processable Thermoelectric Materials
摘要： In the present work, we detail a fast and simple solution-based method to synthesize hexagonal SnSe2 nanoplates (NPLs) and textured SnSe2 nanomaterials. We also demonstrate that the same strategy can be used to produce orthorhombic SnSe nanostructures and nanomaterials. NPLs are grown through a screw dislocation-driven mechanism. This mechanism typically results in pyramidal structures, but we demonstrate here that the growth from multiple dislocations results in flower-like structures. Crystallographically textured SnSe2 bulk nanomaterials obtained from the hot pressing of these SnSe2 structures display highly anisotropic charge and heat transport properties and thermoelectric (TE) figures of merit limited by relatively low electrical conductivities. To improve this parameter, SnSe2 NPLs are blended here with metal nanoparticles. The electrical conductivities of the blends are significantly improved with respect to bare SnSe2 NPLs, what translates into a three-fold increase of the TE figure of merit, reaching unprecedented ZT values up to 0.65.
关键词： SnSe2,reactive ink,thermoelectricity,crystallographically textured nanomaterial,modulation doping
更新于2025-09-23 15:21:01
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Combined solar concentration and carbon nanotube absorber for high performance solar thermoelectric generators
摘要： Solar thermoelectric generators (STEGs) is one of the most important technologies for solar energy conversion. However, the inefficiency due to coupling constraints such like low working temperature and dimensionless figure of merit of the thermoelectric materials, also known as material’s ZT value, has been hampering the development of STEGs for a time. Here we demonstrate a high performance STEG system combined with solar concentrators and carbon nanotubes (CNTs) absorber, which can greatly improve the solar-thermal conversion process. The proposed STEG system enables a peak efficiency of 4.3% with solar concentration of 78, and a maximum power of 11.2 W at 106× suns. The enhanced efficiency is ensured by the optimized system thermodynamics due to the combination of solar concentration devices and CNT based solar absorber. Our design provides a universal prototype of solar thermal energy recovery system for distributed energy harvesting and deep-space explorations.
关键词： Thermodynamics,Carbon nanotube,Solar concentration,Thermoelectricity,Energy harvesting
更新于2025-09-19 17:15:36
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Can Thermodynamics Guide Us to Make Better Solar Cells?
摘要： Thermodynamics has provided a powerful tool to study radiation and its conversion into useful work. Starting from the so-called Shockley’s paradox, this article discusses the thermodynamic view of fundamental losses to photovoltaic conversion, and how thermodynamics enters the charge-carrier transport in semiconductors and heat-exchange processes at p-n junctions. Turning to photon flows, considerations based on detailed balance and reciprocity provide a comprehensive picture of the voltage produced by the solar cell in the presence of nonradiative recombination. We shall use these tools to examine several topics under recent discussion, including photon recycling and hot-carrier conversion based on thermoelectricity.
关键词： thermodynamics,thermoelectricity,solar energy,Photovoltaic cells
更新于2025-09-12 10:27:22
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Interfacing boron monophosphide with molybdenum disulphide for an ultrahigh performance in thermoelectrics, 2D excitonic solar cells and nanopiezotronics
摘要： Stable ultrathin 2D van der Waals (vdW) heterobilayer, based on the recently synthesized boron monophosphide (BP) and the widely studied molybdenum disulphide (MoS2), has been systematically explored for the conversion of waste heat, solar energy and nanomechanical energy into electricity. It shows a gigantic figure of merit (ZT) > 12 (4) for p (n)-type doping at 800 K, which is the highest ever reported till date. At room temperature (300 K), ZT reaches 1.1 (0.3) for p(n)-type doping which is comparable to experimentally measured ZT=1.1 on PbTe-PbSnS2 nanocomposite at 300 K. While it outweighs the Cu2Se-CuInSe2 nanocomposite (ZT=2.6 at 850 K) and the theoretically calculated ZT = 7 at 600 K on silver halides. Lattice thermal conductivity (???? ~ 49 Wm-1K-1) calculated at room temperature is lesser than that of black phosphorene (78 Wm-1K-1) and arsenene (61 Wm-1K-1). The nearly matched lattice constants in the commensurate lattices of the constituent monolayers helps to preserve the direct band gap at the K point in the type II vdW heterobilayer of MoS2/BP, where BP and MoS2 serve as donor and acceptor materials respectively. An ultrahigh carrier mobility ~ 20 × 103 cm2V-1s-1 is found, which exceeds that of previously reported transition metal dichalcogenide based vdW heterostructures. The exciton binding energy (0.5 eV) is close to that of MoS2 (0.54 eV) and C3N4 (0.33 eV) single layers. The calculated power conversion efficiency (PCE) in monolayer MoS2/BP heterobilayer exceeds 20%. It surpasses the efficiency in MoS2/p-Si heterojunction solar cells (5.23%) and competes with the theoretically calculated ones, listed in the manuscript. Furthermore, high optical absorbance (~105 cm-1) of visible light and small conduction band offset (0.13 eV) makes MoS2/BP very promising in 2D excitonic solar cells. Out-of-plane piezoelectric strain coefficient, ??33 ~ 3.16 pm/V, is found to be enhanced four-fold (~14.3 pm/V) upon applying 7% vertical compressive strain on the heterobilayer, which corresponds to ~1 kBar of hydrostatic pressure. Such a high out-of-plane piezoelectric coefficient, which can tune top-gating effects in ultrathin 2D nanopiezotronics, is a relatively new finding. As BP has been synthesized recently, experimental realization of the multifunctional, versatile MoS2/BP heterostructure would be highly feasible.
关键词： first-principles calculations,piezoelectricity,thermoelectricity,solar energy conversion efficiency,excitonic solar cells
更新于2025-09-12 10:27:22
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Heat-Recovery Solar Cell
摘要： Heat-recovery (HERC) solar cell—a concept of solar cells utilizing the heat for improving the power conversion e?ciency—is presented. HERC solar cell, characterized by an absorber hotter than electrodes, recovers heat as electricity to have high conversion e?ciency exceeding the detailed balance limit when carrier-energy ?ltering is employed. Being di?erent from hot-carrier solar cells, HERC solar cell does not require fast carrier extraction within the thermalization time, which largely improves its feasibility (feasible even with Si). An increment in the conversion e?ciency originates from thermoelectricity produced by the temperature di?erence. Requirements for materials of the ?ltering layers are also given based on a nonideal device simulation with the thermoelectric properties.
关键词： Si solar cells,Heat-recovery solar cell,carrier-energy filtering,thermoelectricity,power conversion efficiency
更新于2025-09-11 14:15:04
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Multiphysics THz Antenna Simulations
摘要： The electrical response of an antenna-coupled nanothermocouple depends on how well the antenna converts incident optical energy to heat, and how this heat is converted to electrical signals by the nanothermocouples. In this paper, we study by COMSOL simulations the heat dissipated in dipole antennas operating at 600 GHz to maximize the temperature at the center of the antenna where the nanothermocouples are attached. We study antennas constructed from all-Au, all-Ni, and Au with Ni center segment. We also study the heat loss into the Si substrate, and use various thicknesses of SiO2 for thermal insulation from the substrate. We also discuss our simulation setup and our symmetric, geometry-independent mesh structure to avoid a variety of simulation errors and artifacts.
关键词： Simulation,Nanotechnology,Thermoelectricity,Thermoelectric devices,Antennas
更新于2025-09-04 15:30:14