An Innovative Compact Split-Ring-Resonator-Based Power Tiller Wheel-Shaped Metamaterial for Quad-Band Wireless Communication

A split-ring resonator (SRR)-based power tiller wheel-shaped quad-band "-negative metamaterial is presented in this research article. This is a new compact metamaterial with a high effective medium ratio (EMR) designed with three modified octagonal split-ring resonators (OSRRs). The electrical dimension of the proposed metamaterial (MM) unit cell is 00.086λ × 0.086λ, where λ is the wavelength calculated at the lowest resonance frequency of 2.35 GHz. Dielectric RT6002 materials of standard thickness (1.524 mm) were used as a substrate. Computer simulation technology (CST) Microwave Studio simulator shows four resonance peaks at 2.35, 7.72, 9.23 and 10.68 GHz with magnitudes o

Modified Hexagonal Split Ring Resonator Based on an Epsilon-Negative Metamaterial for Triple-Band Satellite Communication

A triple-band epsilon-negative (ENG) metamaterial based on a split ring resonator (SSR) with a modified hexagonal-shaped metal strip proposed in this study is a new combination of a single slit square resonator and a modified hexagonal-shaped metal strip. The desired unit cell FR-4 (lossy) that was selected as the substrate was 1.6 mm thick. Following the assessment of the unit cell, a high-frequency electromagnetic simulator like the computer simulation technology (CST) microwave studio was applied to assess the S-parameters. The proposed design exhibited resonance at 2.89, 9.42, and 15.16 GHz. The unit cell also demonstrated negative permittivity in the frequency ranges 2.912–3.728 GHz, 9.552–10.144 GHz, and 15.216–17.328 GHz, along with a negative refractive index. An effective medium ratio (EMR) of 11.53 is an indicator of the goodness of the metamaterial unit cell. It is deliberate at the lowermost resonance frequency of 2.89 GHz. Moreover, the simulated results that were validated using HFSS and equivalent circuit model indicated slight variations. The proposed design was finalised based on several parametric studies, including design optimisation, different unit cell sizes, various substrate materials, and different electromagnetic (EM) field propagations. The proposed triple band (S, X, and Ku bands) negative permittivity metamaterial unit cell can be utilised for various wireless applications, such as microwave communication, satellite communication, and long-distance radio communication

A New Compact Split Ring Resonator Based Double Inverse Epsilon Shaped Metamaterial for Triple Band Satellite and Radar Communication

This study presents a double-inverse-epsilon-shaped, triple-band epsilon-negative (ENG) metamaterial with two split ring resonators (SRRs). The proposed unit cell comprises a single slit two SRRs with two inverse-epsilon-shaped metal bits. Rogers RT6002, of dimension 10 × 10 × 1.524 mm3, is used as a substrate. An electromagnetic simulator CST microwave studio is used to investigate the effective medium parameters of the material. The proposed metamaterial shows three resonance peaks that are demarcated at the frequencies 2.38 GHz, 4.55 GHz and 9.42 GHz consecutively. The negative permittivity of the metamaterial is observed at the frequency ranges of 2.39–2.62 GHz, 4.55–4.80 GHz and 9.42–10.25 GHz. The goodness of the material was presented by the effective medium ratio (EMR) of the unit cell at 12.61. In addition, the simulated results are authenticated by using different electromagnetic simulators such as HFSS and ADS for the equivalent circuit model, which exhibits insignificant disparity. The anticipated scheme was finalised through some parametric analyses, together with configuration optimisation, different unit cell dimensions, several substrate materials, and altered electromagnetic (EM) field transmissions. The proposed triple band (S-, C- and X-bands) with negative permittivity (ε) metamaterial is practically used for numerous wireless uses, for instance, far distance radar communication, satellite communication bands and microwave communication

An Innovative Compact Split-Ring-Resonator-Based Power Tiller Wheel-Shaped Metamaterial for Quad-Band Wireless Communication

A split-ring resonator (SRR)-based power tiller wheel-shaped quad-band ℇ-negative metamaterial is presented in this research article. This is a new compact metamaterial with a high effective medium ratio (EMR) designed with three modified octagonal split-ring resonators (OSRRs). The electrical dimension of the proposed metamaterial (MM) unit cell is 0.086λ × 0.086λ, where λ is the wavelength calculated at the lowest resonance frequency of 2.35 GHz. Dielectric RT6002 materials of standard thickness (1.524 mm) were used as a substrate. Computer simulation technology (CST) Microwave Studio simulator shows four resonance peaks at 2.35, 7.72, 9.23 and 10.68 GHz with magnitudes of −43.23 dB −31.05 dB, −44.58 dB and −31.71 dB, respectively. Moreover, negative permittivity (ℇ) is observed in the frequency ranges of 2.35–3.01 GHz, 7.72–8.03 GHz, 9.23–10.02 GHz and 10.69–11.81 GHz. Additionally, a negative refractive index is observed in the frequency ranges of 2.36–3.19 GHz, 7.74–7.87 GHz, 9.26–10.33 GHz and 10.70–11.81 GHz, with near-zero permeability noted in the environments of these frequency ranges. The medium effectiveness indicator effective medium ratio (EMR) of the proposed MM is an estimated 11.61 at the lowest frequency of 2.35 GHz. The simulated results of the anticipated structure are validated by authentication processes such as array orientation, HFSS and ADS for an equivalent electrical circuit model. Given its high EMR and compactness in dimensions, the presented metamaterial can be used in S-, C- and X-band wireless communication applications

A New Compact Split Ring Resonator Based Double Inverse Epsilon Shaped Metamaterial for Triple Band Satellite and Radar Communication

This study presents a double-inverse-epsilon-shaped, triple-band epsilon-negative (ENG) metamaterial with two split ring resonators (SRRs). The proposed unit cell comprises a single slit two SRRs with two inverse-epsilon-shaped metal bits. Rogers RT6002, of dimension 10 × 10 × 1.524 mm3, is used as a substrate. An electromagnetic simulator CST microwave studio is used to investigate the effective medium parameters of the material. The proposed metamaterial shows three resonance peaks that are demarcated at the frequencies 2.38 GHz, 4.55 GHz and 9.42 GHz consecutively. The negative permittivity of the metamaterial is observed at the frequency ranges of 2.39–2.62 GHz, 4.55–4.80 GHz and 9.42–10.25 GHz. The goodness of the material was presented by the effective medium ratio (EMR) of the unit cell at 12.61. In addition, the simulated results are authenticated by using different electromagnetic simulators such as HFSS and ADS for the equivalent circuit model, which exhibits insignificant disparity. The anticipated scheme was finalised through some parametric analyses, together with configuration optimisation, different unit cell dimensions, several substrate materials, and altered electromagnetic (EM) field transmissions. The proposed triple band (S-, C- and X-bands) with negative permittivity (ε) metamaterial is practically used for numerous wireless uses, for instance, far distance radar communication, satellite communication bands and microwave communication

2,7-Carbazole and thieno[3,4-c]pyrrole-4,6-dione based copolymers with deep highest occupied molecular orbital for photovoltaic cells

Three kinds of donor-acceptor (D-A) type photovoltaic polymers were synthesized based on 2,7-carbazole and thieno[3,4-c]pyrrole-4,6-dione (TPD). The conjugation of weakly electron (e)-donating 2,7-carbazole and strongly e-accepting TPD moieties yielded a deep highest occupied molecular orbital (HOMO) and its energy level was fine-controlled to be -5.72, -5.67 and -5.57 eV through the incorporation of thiophene (T), thieno[3,2-b]thiophene (TT) and bithiophene (BT) as a ??-bridge. Polymer:[6,6]-phenyl-C71 butyric acid methyl ester (PC71BM) based bulk heterojunction solar cells exhibited a high open-circuit voltage (VOC) in the range, 0.86-0.94 V, suggesting good agreement with the measured HOMO levels. Despite the high VOC, the thiophene (or thienothiophene)-containing PCTTPD (or PCTTTPD) showed poor power conversion efficiency (PCE, 1.14 and 1.25%) because of the very low short-circuit current density (JSC). The voltage-dependent photocurrent and photoluminescence quenching measurements suggested that hole transfer from PC71BM to polymer depends strongly on the HOMO level of the polymer. The PCTTPD and PCTTTPD devices suffered from electron-hole recombination at the polymer/PC71BM interfaces because of the insufficient energy offset between the HOMOs of the polymer and PC71BM. The PCBTTPD:PC71BM device showed the best PCE of 3.42% with a VOC and JSC of 0.86 V and 7.79 mA cm-2, respectively. These results show that photovoltaic polymers should be designed carefully to have a deep HOMO level for a high VOC and sufficient energy offset for ensuring efficient hole transfer from PC71BM to the polymer. © 2015 Elsevier B.V. All rights reservedclose0

How Heteroatom Substitution in Donor-Acceptor Copolymers Affects Excitonic and Charge Photogeneration Processes in Organic Photovoltaic Cells

Recent attention has been drawn to expanding the class of polymer-based OPV materials through heteroatom substitution within the repeating units in the main chain of a polymer backbone. We sought to investigate how heteroatom substitution within a donor-acceptor copolymer causes such large variations in the photovoltaic parameters, which cannot be explained considering the variations in the optical band gap alone. Our study applies broadband transient absorption spectroscopy to a series of low-band gap copolymers, wherein the S-position of the benzothiadiazole in the parent polymer structure is substituted for an oxygen (i.e., benzooxadiazole) and selenium (i.e., benzoselenadiazole). Our thin-film morphology measurements reveal unfavorable packing of the oxygen- and selenium-containing polymers near the interfaces with [6,6]-phenyl-C-71-butyric acid methyl ester (PCBM) or in intermixed regions. We explain the device performance differences based upon a sub-optimal blend morphology, resulting in suppressed dissociation of charge-transfer states and, concomitantly, high geminate recombination rates for these systems. Furthermore, the heavy-atom effect of the selenium-containing polymer facilitates access to the triplet manifold. We find that triplet state formation can initially be circumvented by fast charge photogeneration in the finely intermixed morphology of the polymer:PCBM blend; however, this morphology also prevents charge dissociation and ultimately results in recombination to form triplet exciton states. These results provide valuable insights into how heteroatom substitutions affect the thin-film morphology and severe photocurrent loss pathways in polymer solar cells

1,4-Di(3-alkoxy-2-thienyI)-2,5-difluorophenylene: A Building Block Enabling High-Performance Polymer Semiconductors with Increased Open-Circuit Voltages

A new building block, 1,4-di(3-alkoxy-2-thienyl)-2,5-difluorophenylene (DOTFP) with several desirable features such as high backbone planarity, suitably lying highest occupied molecular orbital (HOMO), and good solubility, was developed by inserting an electron-deficient difluorophenylene into the 3,3'-dialkoxy-2,2'-bithiophene (BTOR) unit. Three regioregular D-A(1)-D-A2 type polymers based on DOTFP and benzothiadiazole (BT) derivatives were synthesized and characterized by comparing with a D-A type BTOR-based polymer. The content of highly electron-rich alkoxythiophene is reduced by half in the DOTFP-based polymers versus that of the BTOR-based polymer analogue, which results in a deeper HOMO level and benefits high open-circuit voltage (V-oc) in polymer solar cells (PSCs). Consequently, the DOTFP-ffBT-based solar cells exhibited a significantly improved power conversion efficiency (PCE) of 8.7% and an increased V-oc of 0.84 V compared to the BTOR-ffBT-based solar cells with a PCE of 2.6% and a V-oc of 0.49 V. Additionally, the DOTFP-based polymers showed improved charge transport properties and film morphology than the BTOR-based polymer BTOR-ffBT, resulting in simultaneous enhancement of the short-circuit current (J(sc)) and fill factor (FF) in PSCs. These results demonstrate the great promise of the DOTFP building block for the construction of high-performance photovoltaic polymer semiconductors with increased V(oc)s

Green-, Red-, and Near-Infrared-Emitting Polymer Dot Probes for Simultaneous Multicolor Cell Imaging with a Single Excitation Wavelength

We report newly synthesized fluorescence resonance energy transfer (FRET)-based green-, red-, and near-infrared (NIR)-emitting polymer dot (Pdot) probes. Fluorescent Pdots (similar to 60 nm) were prepared with a green-emissive conjugated polymer (PPDT-P, donor) alone or mixing the donor with a red- or NIR-emitting fluorophore (T-DCS or ITIC, acceptor), where an optically inert matrix polymer [poly(styrene-co-maleic anhydride)] was mixed together to minimize the aggregation-caused quenching by diluting the fluorophores and surface functionalization for further bioconjugation with antibodies for active targeting. Highly fluorescent green-emissive PPDT-P Pdots were prepared with a photoluminescence (PL) quantum efficiency of similar to 30% and the FRET-mediated red and NIR PL was intensified by 5.3-8.5 times (with high FRET ratios of similar to 9) via the efficient energy transfer (FRET efficiency of 80-98%) and antenna effect, compared with the signals obtained via direct excitation of the fluorophores in Pdots. All three types of Pdot/antibody conjugates were simultaneously immunostained to COS-7 cells (showing minimal cross-reactivity), reducing the tedious sequential immunostaining process to a single step. Finally, we obtained high-contrast three-color cell images with little spectral leakthrough by exciting all the probes simultaneously at a single wavelength at 405 nm without the need for a complicated or expensive multiple-excitation setup11Nsci