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Terahertz intersubband transitions in GaAsBi/AlGaAs single quantum well heterostructure
摘要： GaAsBi/AlGaAs single quantum well conduction band structure, energy levels, and their corresponding wavefunctions have been calculated by solving the Schr?dinger equation. The influences of the heterostructure parameters on the intersubband transition (ISBT) frequency within the terahertz (THz) domain have been investigated. The results show that the quantum well width has a great impact on the THz ISBT frequency. In particular, an ISBT with a frequency of 2.611 THz (10.80?meV) has been obtained for specifically optimized parameters. The study of the intersubband optical absorption coefficient (OAC) was centered in the frequency band of 2 – 14 THz ( ~ 8 – 58 meV), therefore the corresponding results are useful for the optimization of THz detectors. Correspondingly, by changing the thickness of the active layer the number of the OAC peaks has been tuned. The dipole matrix element and the Fermi occupation function have been also studied in detail. Furthermore, the influences coming from the incidence angle on the OAC intensity were numerically investigated. The obtained results could be beneficial for the design and the optimization of devices operating in the THz frequency band.
关键词： GaAsBi quantum well,Terahertz region,Intersubband transitions,Optical absorption coefficient,Incidence angle,Active layer thickness
更新于2025-09-19 17:13:59
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High-Performance Emulator for Fixed Photovoltaic Panels
摘要： This paper presents the design and implementation of a photovoltaic emulator, based on an accurate mathematical model of a photovoltaic panel, instead of the look-up table method. The latter requires more memory for increasing accuracy and considering all the desired environmental situations. Furthermore, the proposed approach takes into account the incidence solar angle, as an input parameter, to offer the possibility of evaluating daily losses for different values of tilt angle. The validation of the proposed emulator is carried out by comparing in real-time, both the studied panel output and the emulator output, under variable load, temperature, and irradiation levels. The emulator is able to operate online with connected solar radiation and temperature sensors or offline with recorded measurement vectors. The practical tests were performed on a prototype designed using a MATLAB C MEX S-function, dSPACE board 1104, and a controlled DC/DC converter. The results showed that the emulator was able to behave accurately as the studied photovoltaic panel.
关键词： DC/DC converter,mathematical model,real-time validation,incidence solar angle,photovoltaic emulator
更新于2025-09-19 17:13:59
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Light Harvesting at Oblique Incidence Decoupled from Transmission in Organic Solar Cells Exhibiting 9.8% Efficiency and 50% Visible Light Transparency
摘要： For many years, it has been recognized that potential organic photovoltaic cells must be integrated into elements requiring high transparency. In most of such elements, sunlight is likely to be incident at large angles. Here it is demonstrated that light transmission can be largely decoupled from harvesting by optically tailoring an infrared shifted nonfullerene acceptor based organic cell architecture. A 9.67% power conversion efficiency at 50° incidence is achieved together with an average visual transmission above 50% at normal incidence. The deconstruction of a 1D nanophotonic structure is implemented to conclude that just two λ/4 thick layers are essential to reach, for a wide incidence angle range, a higher than 50% efficiency increase relative to the standard configuration reference. In an outdoor measurement of vertically positioned 50% visible transparent cells, it is demonstrated that 9.80% of sunlight energy can be converted into electricity during the course of 1 day.
关键词： transparent solar cells,near-infrared ternary blends,1-D nanophotonic structures,optical trapping,oblique incidence
更新于2025-09-19 17:13:59
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[IEEE 2019 Thirteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Rome, Italy (2019.9.16-2019.9.21)] 2019 Thirteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Wide Band Polarization Converter Graphene Metasurface for Mid-Infrared Band
摘要： Wide band, insensitive incidence angle graphene metasurface for polarization conversion is introduced in this work. A high Polarization Conversion Ratio (PCR) is verified in Mid-Infrared band by using a graphene as an upper conductor for metasurface. The metasurface construction is composed of a single layer of graphene, which has a half ring slots with rectangular slot connecting between them while the whole shape is rotated with 45o. Silicon dioxide substrate is used with a metal backed ground. The simulation results of the proposed metasurface indicate that a linearly polarized incident wave is converted to a circular polarized one over more than one THz along the Mid-Infrared frequency band. PCR has a maximum value of approximately 98% at 1.45 THz. The polarization conversion ratio is studied for different angles of incidence, with stable value for a wide range of incident angles.
关键词： Insensitive incidence angle,Graphene metasurface,Wide band,Mid-Infrared band,Polarization Conversion Ratio (PCR)
更新于2025-09-16 10:30:52
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Reliability of Terrestrial Laser Scanner Measurement in Slope Monitoring
摘要： Dense 3D point clouds provided by terrestrial laser scanner (TLS) has demonstrated significant reliability of TLS in landslide monitoring. However, existence of errors in measurement is inevitable which eventually has decreased the quality of TLS data. To concretely measure the capability of TLS in landslide monitoring, this study has performed two epoch measurements using tacheometry (for benchmarking) and TLS (Topcon GLS-2000) at Kulim Techno City, Kedah, Malaysia. Sixteen (16) artificial targets were well-distributed on the slope to determine the accuracy of the employed TLS. Results obtained revealed that Topcon GLS-2000 provides 0.006m of accuracy. However, the presence of high incidence angles in TLS measurement has limited the capability to identify the significant displacement of the targets.
关键词： Slope Monitoring,Incidence Angles,Terrestrial Laser Scanner,Landslide Monitoring,Accuracy
更新于2025-09-16 10:30:52
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Broadband Solar Energy Absorption in Plasmonic Thin-Film Amorphous Silicon Solar Cell
摘要： Improving the light absorption in thin-?lm solar cell is essential for enhancing e?ciency and reducing cost. Here, we propose an ultra-broadband amorphous silicon solar cell based on a periodic array of titanium ring-shaped metasurfaces, which achieves more than 90% absorptance in the visible range of the solar spectrum. The surface plasmon resonance supported by the nanoparticles together with the resonance induced by the metal–insulator–metal Fabry–Perot cavity leads to this broadband absorption. The impact of various materials of functional layers and the geometric structure of the nanoparticle on absorption performance is discussed in detail, and super broadband resonance is achieved after optimization. Moreover, the optimized solar cell is tested for di?erent solar incidence angles and it is found that the structure exhibits high absorption e?ciency even at large angles. Thus, the proposed solar cell design may be bene?cial for most of the photovoltaic applications.
关键词： nanoparticle,antire?ection coating,solar incidence angle,broadband absorption
更新于2025-09-16 10:30:52
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Rooma??Temperature Partial Conversion of ?±a??FAPbI <sub/>3</sub> Perovskite Phase via PbI <sub/>2</sub> Solvation Enables Higha??Performance Solar Cells
摘要： The two-step conversion process consisting of metal halide deposition followed by conversion to hybrid perovskite has been successfully applied toward producing high-quality solar cells of the archetypal MAPbI3 hybrid perovskite, but the conversion of other halide perovskites, such as the lower bandgap FAPbI3, is more challenging and tends to be hampered by the formation of hexagonal nonperovskite polymorph of FAPbI3, requiring Cs addition and/or extensive thermal annealing. Here, an efficient room-temperature conversion route of PbI2 into the α-FAPbI3 perovskite phase without the use of cesium is demonstrated. Using in situ grazing incidence wide-angle X-ray scattering (GIWAXS) and quartz crystal microbalance with dissipation (QCM-D), the conversion behaviors of the PbI2 precursor from its different states are compared. α-FAPbI3 forms spontaneously and efficiently at room temperature from P2 (ordered solvated polymorphs with DMF) without hexagonal phase formation and leads to complete conversion after thermal annealing. The average power conversion efficiency (PCE) of the fabricated solar cells is greatly improved from 16.0(±0.32)% (conversion from annealed PbI2) to 17.23(±0.28)% (from solvated PbI2) with a champion device PCE > 18% due to reduction of carrier recombination rate. This work provides new design rules toward the room-temperature phase transformation and processing of hybrid perovskite films based on FA+ cation without the need for Cs+ or mixed halide formulation.
关键词： FAPbI3,two-step conversion,high performance,hybrid perovskite solar cells,quartz-crystal microbalance,in situ grazing incidence wide angle x-ray scattering
更新于2025-09-16 10:30:52
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An industry-relevant method to determine material-specific parameters for ultra-short pulsed laser ablation of cemented carbide
摘要： In recent years, it has been shown that ultra-short pulsed lasers can be used for the post processing and the fabrication of cutting tools. This new manufacturing technology can compete with the mainly used grinding process due to its ability to ablate materials independent of their hardness and without any wear. The knowledge of material properties is necessary for an optimal choice of machining parameters and the prediction of the ablation process. Measuring them is challenging, especially for inhomogeneous, ultra-hard materials. In this paper, an industry-relevant method is presented, which enables to determine the threshold fluence and the optical properties of cemented carbide. The required material-specific parameters are derived from simple ablation experiments, which are carried out on a modern laser machining center. Finally, the results are used to present a formula to calculate the material removal rate at different angles of incidence of the laser beam.
关键词： Neuenschwander model,ultra-short pulse laser machining,ablation efficiency,inclined incidence,threshold fluence,ablation rate,cemented carbide
更新于2025-09-12 10:27:22
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Post-processing of additively manufactured cutting edges by laser ablation
摘要： In the packaging industry, cutting dies are used to process paper based material. The dies are mainly manufactured via steel strip principle, which consists of many manual steps and is difficult to automate. Laser material processing represents a promising approach to simplify manufacturing. This study realized additively manufactured cutting edges post-processed by laser ablation to achieve a defined final profile shape. First verification shows that laser ablation appears to be attractive for finishing of additively manufactured cutting edges.
关键词： angle of incidence,additive manufacturing,hybrid production,laser ablation,cutting edge,post-processing
更新于2025-09-12 10:27:22
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Evaluation of exciton diffusion length in highly oriented fullerene films of fullerene/p-Si(100) hybrid solar cells
摘要： Highly oriented fullerene (C60) films on p-Si (100) substrates were fabricated to evaluate the crystallinity dependent exciton diffusion length of C60 (LC60). The crystal structure of the C60 films was examined using grazing incidence X-ray diffraction (GIXD). The results of an in-plane rocking scan and a pole figure suggested that a 12-fold-symmetry crystal was grown with the C60(111) surface interfaced to the Si(100) substrate. The photovoltaic characteristics of the oriented C60/p-Si(100) hybrid solar cells were evaluated. A masking effect was clearly evident in the incident photon-to-current conversion efficiency (IPCE) spectra. LC60 was evaluated using both experimental IPCE spectra and that produced by one-dimensional-optical simulation. It was concluded that LC60 for highly oriented C60 was 60 nm, which was longer than that of disordered C60 films.
关键词： crystal growth,hybrid solar cells,fullerene (C60),exciton diffusion length,grazing incidence X-ray diffraction (GIXD),masking effect
更新于2025-09-11 14:15:04