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Design and characterization of the double-layered defected ground structure transmission line with less radiation loss
摘要： A double-layered DGS transmission line is proposed with a smaller DGS size and less radiation loss. Changing the air boundary to a dielectric boundary reduces the effective electric length at the DGS aperture area. An equivalent circuit model is introduced to analyze the DGS transmission line and the resonator circuit designs. Due to the increase in the effective dielectric constant, the proposed structure can be realized with less sensitivity to metallic environments. From the experimental results, the proposed double-layered DGS can achieve a reduction of 90.1% in size and insensitivity at up to 5 mm of separation from the DGS aperture to the metallic plate.
关键词： equivalent circuit models,effective dielectric constants,radiation loss,size reduction,defected ground structures
更新于2025-09-23 15:23:52
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Trade‐Off between Exciton Dissociation and Carrier Recombination and Dielectric Properties in Y6‐Sensitized Nonfullerene Ternary Organic Solar Cells
摘要： Organic photovoltaics (OPVs) have emerged as a promising renewable energy generation technology in past decades. However, the deep understanding of the details in exciton dissociation and carrier recombination in ternary organic solar cells (OSCs) is still lacking. Herein, a novel ternary OSC based on a PTB7-Th:Y6:ITIC blend with a power conversion efficiency (PCE) enhancement of 29% is reported. A trade-off is surprisingly found to exist between the exciton dissociation and carrier recombination process. The addition of nonfullerene acceptor Y6 in the ternary blend is found to create an efficient exciton dissociation process but accelerates the free carrier recombination process. Dielectric properties are also studied for ternary OSCs. The addition of Y6 into the binary blend is found to tune down the dielectric constant of the active layer and as a result accelerates the carrier recombination. The best performance is obtained for PTB7-Th:Y6(5 wt%):ITIC(95 wt%)-based ternary devices. In addition to its balanced charge carrier mobility and efficient charge extraction process, PTB7-Th:Y6(5 wt%):ITIC(95 wt%)-based ternary devices reach a balance in the trade-off between the exciton dissociation and carrier recombination process and thus achieve the highest short-circuit current density (Jsc) value.
关键词： nonfullerene,carrier recombination and dielectric constants,ternary,organic solar cells,exciton dissociation
更新于2025-09-19 17:13:59
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First-principles investigation of the electronic band structures and optical properties of quaternary <i>A</i> Ba <i>MQ</i> <sub/>4</sub> ( <i>A</i> = Rb, Cs; <i>M</i> = P, V; and <i>Q</i> = S) metal chalcogenides
摘要： In this paper, we study the optoelectronic properties of quaternary metal chalcogenide semiconductor ABaM Q4 (A = Rb, Cs; M = P, V; and Q = S) compounds using state-of-the-art density functional theory (DFT) with TB-mBJ approximation for the treatment of exchange-correlation energy. In particular, the electronic and optical properties of the relaxed geometries of these compounds are investigated. Our first-principles ab-initio calculations show that the CsBaPS4 and RbBaPS4 compounds have direct bandgaps whereas the CsBaVS4 compound exhibits indirect bandgap nature. Importantly, the theoretically calculated values of the bandgaps of the compounds are consistent with experiment. Furthermore, our analysis of the electronic charge densities of these compounds indicates that the above quaternary chalcogenides have mixed covalent and ionic bonding characters. The effective masses of these compounds are also calculated which provide very useful information about the band structure and transport characteristics of the investigated compounds. Similarly, high absorptivity in the visible and ultraviolet regions of the electromagnetic spectrum possibly predicts and indicates the importance of these materials for potential optoelectronic applications in this range.
关键词： energy band structure,electronic charge densities,optical conductivity,Chalcogenides,refractive index,dielectric constants,optical reflectivity
更新于2025-09-09 09:28:46