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[IEEE 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Miramar Beach, FL, USA (2019.8.19-2019.8.21)] 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Nonlinear Metasurfaces for Optical Applications
摘要： A novel planar ultrathin electronically steerable parasitic array radiator (ESPAR) is presented in this paper. Through theoretical analysis of the electric fields of orthogonally crossed dipoles in phase quadrature, it is found that the crossed dipoles radiate linearly polarized wave with a rotational electric field in the azimuth plane. This characteristic is then utilized to design a planar crossed dipole ESPAR, termed as “CD-ESPAR.” Furthermore, a simple but effective impedance matching method is also proposed and analyzed. To verify these concepts, a prototype with compact size and very low profile (0.42 λ0 × 0.42 λ0 × 0.006 λ0) resonating at 2.3 GHz is designed, fabricated, and measured. The measured results indicate that the proposed antenna achieves more than 17.8% impedance bandwidth and can produce four directional beams, covering the whole azimuth plane. Owing to its planar ultrathin structure, compact size, electronically beam-switching ability, low power, and low cost characteristics, it is promising for applications in wireless communications.
关键词： Beam-switching,planar antenna,smart antenna,crossed dipoles,electronically steerable parasitic array radiator (ESAPR)
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Spectral Features of a Multi-Periodical Metamaterials
摘要： We numerically investigate the spectral properties of multi-periodic metamaterials of various configurations (the planar double-periodic photonic crystal and the bulk double-periodic magnetophotonic crystal) in the frequency range 15-45 GHz. In the first part of this paper we describe investigation of structure of the planar double periodic photonic crystal (PDPPC) which consists of two planar photonic crystals with large and small periods. A PDPPC unit cell consists of a series-connected narrow and wide segments of a microstrip transmission line. In the second part of this paper we will discuss results of investigation of a double-periodic magnetophotonic crystal (DPMPC) which consists of 3 unit cells. Each cell consists of periodically located 9 dielectric layers of quartz and teflon. On the border of the cell there is one layer of ferrite. We showed that both for a PDPPC and for a DPMPC in the transmission spectrum of these structures under study, a number of features arise: namely, narrow transmission peaks caused by the superposition of two spectra (with large and small periods) are observed in the stop bands of the spectrum. Such features may further allow the creation of a narrow-band filter for several frequencies for both planar structures and bulk ones.
关键词： magnetophotonic crystal,multi-periodical metamaterial,stop band,pass band,planar photonic crystal,transmission spectrum
更新于2025-09-19 17:13:59
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Low Temperature Processed Highly Efficient Hole-Transport-Layer Free Carbon-based Planar Perovskite Solar Cells with SnO2 Quantum Dot Electron-Transport-Layer
摘要： The use of expensive hole transport layer (HTL) and back contact along with the stability issue of perovskite solar cells have been a detrimental factor when it comes to commercialization of the technology. In addition, high-temperature and long annealing time processed electron transport layers (ETLs, e.g., TiO2) prevents the flexible solar cell application in most polymer substrate. Herein, we opted for HTL-free carbon electrodes owing to their low-cost production and superior stability in air, compared to their noble metal counterparts. In this work, we fabricate planar perovskite solar cells using low-temperature solution processed SnO2 quantum dots (QDs) as ETL, which offers significant advantages over high temperature processed ETLs due to its excellent electron extraction and hole blocking ability. In addition, by integrating a low cost and stable carbon electrode, an impressive energy conversion efficiency of 13.64% with a device architecture glass/In doped SnO2/QD-SnO2/Perovskite/Carbon under 1 sun illumination at ambient conditions have been achieved. This work paves the way to achieve fully low-temperature processed printable perovskite solar cells (PSCs) at an affordable cost by integrating the QD SnO2 ETL and Carbon electrode.
关键词： low-temperature process,planar perovskite solar cells,hole transport layer free,carbon electrode,SnO2 Quantum Dot
更新于2025-09-19 17:13:59
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Improved Design Techniques for High Performance Planar Waveguide Slot Arrays
摘要： Waveguide slot antennas and arrays date back to the forties, but they are still nowadays very popular as high-frequency antennas, mainly for RADAR and communication systems. In this paper we describe the main limitations and drawbacks of waveguide slot arrays configurations, and the possible countermeasures proposed in the literature, focusing on the improved design technique available for high performance planar waveguide slot arrays.
关键词： high performance planar waveguide slot arrays,Waveguide slot antennas,communication systems,RADAR
更新于2025-09-19 17:13:59
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Nonconfinement Structure Revealed in Dion–Jacobson Type Quasi‐2D Perovskite Expedites Interlayer Charge Transport
摘要： Dion–Jacobson (DJ) type 2D perovskites with a single organic cation layer exhibit a narrower distance between two adjacent inorganic layers compared to the corresponding Ruddlesden–Popper perovskites, which facilitates interlayer charge transport. However, the internal crystal structures in 2D DJ perovskites remain elusive. Herein, in a p-xylylenediamine (PDMA)-based DJ perovskite bearing bifunctional NH3+ spacer, the compression from confinement structure (inorganic layer number, n = 1, 2) to nonconfinement structure (n > 3) with the decrease of PDMA molar ratio is unraveled. Remarkably, the nonconfined perovskite displays shorter spacing between 2D quantum wells, which results in a lower exciton binding energy and hence promotes exciton dissociation. The significantly diminishing quantum confinement promotes interlayer charge transport leading to a maximum photovoltaic efficiency of ≈11%. Additionally, the tighter interlayer packing arising from the squeezing of inorganic octahedra gives rise to enhanced ambient stability.
关键词： exciton,planar perovskite solar cells,nonconfinement structures,Dion–Jacobson,quasi-2D perovskite
更新于2025-09-19 17:13:59
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Low Temperaturea??Processed Zr/F Coa??Doped SnO <sub/>2</sub> Electron Transport Layer for Higha??Efficiency Planar Perovskite Solar Cells
摘要： The energy band position and conductivity of electron transport layers (ETLs) are essential factors that restrict the efficiency of planar perovskite solar cells (p-PSCs). Tin oxide (SnO2) has become a primary material in ETLs due to its mild synthesis condition, but its low conduction band position and limited intrinsic carriers are disadvantageous in electron transport. To solve these problems, this work exquisitely designs a Zr/F co-doped SnO2 ETL. The doping of Zr can raise the conduction band of SnO2, which reduces the energy barrier in electron extraction and inhibits the interface recombination between the ETL and perovskite. The open-circuit voltage (VOC) of p-PSCs consequently increases. F? doping belongs to n-type doping. Thus, it equips SnO2 with a large number of free electrons and improves the conductivity of the ETL and short-circuit current (JSC). The device based on Zr/F co-doped ETL achieves a high efficiency of 19.19% and exhibits a reduced hysteresis effect, which is more satisfactory than that of a pristine device (17.35%). Overall, our research successfully adjusts the energy band match and boosts the conductivity of ETL via Zr/F co-doping. The results provide an effective strategy for fabricating high-efficiency p-PSCs.
关键词： electron transport layer,Zr/F co-doping,energy level match,planar perovskite solar cell,tin oxide (SnO2)
更新于2025-09-19 17:13:59
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Highly efficient planar heterojunction perovskite solar cells with sequentially dip-coated deposited perovskite layers from a non-halide aqueous lead precursor
摘要： High-performance planar heterojunction (PHJ) perovskite solar cells (PrSCs) with MAPbI3 perovskite films were fabricated using a facile, environmentally benign, efficient and low-cost dip-coating deposition approach on a bilayered ZnO/TiO2 electron transport system from aqueous non-halide Pb(NO3)2. Outstanding performance of PrSCs was achieved due to the PHJ configuration of FTO/TiO2/ZnO/MAPbI3/spiro-OMeTAD/MoO3/Ag. These PHJ PrSCs exhibited better performance and stability with thinner ZnO layers in contrast to those with mesoporous TiO2 scaffolds, indicating that the thickness of the ZnO layer in the PHJ architecture significantly affected the surface coverage, morphology, crystallinity, and stability of the MAPbI3 perovskite films processed by dip-coating deposition.
关键词： ZnO/TiO2 electron transport system,perovskite solar cells,planar heterojunction,dip-coating deposition,aqueous non-halide Pb(NO3)2
更新于2025-09-19 17:13:59
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Record Photocurrent Density over 26a??mAa??cm <sup>a??2</sup> in Planar Perovskite Solar Cells Enabled by Antireflective Cascaded Electron Transport Layer
摘要： Here an antireflective cascaded SnO2/TiO2-Cl electron transport layer (ETL) is devised to enhance the performance of planar perovskite solar cells (PSCs). The primary optical reflection of planar PSCs at the front side can be dramatically reduced by using cascaded ETL. Based on this strategy, we achieved a record-high short-circuit current density of 26.1 mA cm-2 and a high PCE of 22.9% in FAPbI3-based planar PSCs.
关键词： planar perovskite solar cells,cascaded electron transport layers,anti-reflection,bilayer,short-circuit current density
更新于2025-09-19 17:13:59
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Practical Chromatic Aberration Correction in Virtual Reality Displays Enabled by Cost‐Effective Ultra‐Broadband Liquid Crystal Polymer Lenses
摘要： Chromatic aberration (CA) is a critical issue in immersive virtual reality displays. The current digital compensation method can reduce the CA by pre-processing the image contents but at the cost of extra memory space, processing time, and power consumption. Moreover, it is not possible to digitally compensate the CA within each color channel. Here, a practical optical approach is presented to correct the CAs, including the sub-channel ones, in the virtual reality system, whose functionality is verified by both ray-tracing analysis and experimental results. In this device, a compact ultra-broadband Pancharatnam-Berry phase lens (PBL) with complex axial molecular structure is fabricated and then hybridized with a refractive Fresnel lens. Due to their opposite chromatic dispersion, the system’s CA is significantly reduced. To eliminate ghost image from the zero-order leakage of PBL, a broadband circular polarizer is implemented to block the stray light. As a result, clear image within the entire 100° field-of-view is achieved. The proposed large-size cost-efficient broadband wide-view flat optics can practically benefit not only virtual reality displays but also general imaging systems for practical applications and scientific research.
关键词： metasurfaces,planar lenses,virtual reality,liquid crystal polymers,chromatic aberration
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - 2.1 a?? 2.2 eV AlGaInP solar cells grown by molecular beam epitaxy
摘要： In the advanced manufacturing industry, planar switched reluctance motors (PSRMs) have proved to be a promising candidate due to their advantages of high precision, low cost, low heat loss, and ease of manufacture. However, their inverse force function, which provides vital phase current command for precise motion, is highly nonlinear and hard to be accurately modeled. This paper proposes a novel inverse force function using sparse least squares support vector machines (LS-SVMs) to achieve nonlinear modeling for precise motion of a PSRM. The required training and testing sets of sparse LS-SVMs are ?rst obtained from experimental measurement. A sparse LS-SVMs regression is further developed using training set to accurately model the inverse force function. Accordingly, the function is tested via the testing set to assess its feasibility. Finally, the proposed approach is applied to the PSRM system with dSPACE controller for trajectory tracking, and its effectiveness and superior performance are veri?ed through experimental results.
关键词： Inverse force function,least squares support vector machines (LS-SVMs),phase current estimation,nonlinear modeling,planar switched reluctance motors (PSRMs)
更新于2025-09-19 17:13:59