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oe1(光电查) - 科学论文

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出版时间
  • 2019
研究主题
  • parasitic patches
  • Direct coupled
  • gap coupled
  • hybrid coupled
  • composite mode
应用领域
  • Electronic Science and Technology
机构单位
  • SVKM’s DJSCE
  • DIAT
362 条数据
?? 中文（中国） ▾

  • Nitrogen-doped graphene quantum dots prepared by electrolysis of nitrogen-doped nanomesh graphene for the fluorometric determination of ferric ions

    摘要： Nitrogen-doped graphene quantum dots (N-GQDs) were synthesized by direct electrolysis of a carbon cloth electrode coated with nitrogen-doped nanomesh graphene (NG) in high yield (~ 25%). The N-GQDs emit intense blue fluorescence with a quantum yield (QY) of 10% ± 3%. Meanwhile, the N-GQDs are rich in hydroxyl, carboxyl, basic pyridinic nitrogen, and nitro groups, which are conducive to strengthen the interaction between N-GQDs and Fe3+ for highly sensitive determination of Fe3+ ions. Specifically, the determination for Fe3+ was conducted at different concentrations of N-GQD solution with a wide linear range of 10–1000 μM (150 μg·mL?1) and a low detection limit of 0.19 μM (10 μg·mL?1). Moreover, the fluorescence quenching mechanism illustrated that the functional groups generated by electrochemical oxidation enhanced the interaction of N-GQDs and Fe3+, and the narrow band gap (2.83 eV) of N-GQDs accomplished electron transfer from N-GQDs to Fe3+ easily.

    关键词： Fluorescence lifetime,Band gap,Dynamic quenching,Carbon cloth electrode,Electrochemical oxidation

    更新于2025-09-23 15:21:01

  • Electronic structure and transport properties of graphene/h-BN controlled by boundary potential and magnetic field

    摘要： We study the band structure of the lattice-matched graphene/h-BN bilayer system in the most stable configuration. An effective way to individually manipulate the edge state by the boundary potentials is proposed. It is shown that the boundary potential can not only shift and deform the edge bands, but also modify the energy gap. We also explore the transport properties of graphene/h-BN under a magnetic field. The boundary potential can change the distribution of the edge states, resulting in an interesting evolution of the quantized conductance.

    关键词： energy gap,transport property,Lattice-matched graphene/h-BN,boundary potential

    更新于2025-09-23 15:21:01

  • Optical properties of poly (ethyl methacrylate) - cellulose acetate propionate blend film irradiated with Nd:YAG laser

    摘要： Poly (ethyl methacrylate) (PEMA) - cellulose acetate propionate (CAP) blend film was prepared using the cast technique. A Q-switched Nd: YAG laser beam with a wavelength of 266 nm, a pulse duration of 10-ns, a repetition rate10 Hz and 0.018 J/cm2 fluence was used to irradiate the prepared film. The optical absorption of pristine and irradiated sample was studied within 200–500 nm wavelength region. The absorbance increases with laser irradiation time over the full wavelength region which is attributed to an increase of the crosslinking network. Examining Tauc plots revealed a transition of the direct allowed type with optical energy gap value of 4.92 eV for the pristine blend film which has decreased to 4.30 eV after laser irradiation for 90 min. The refractive index, finesse coefficient, dielectric function, Brewster, and critical angles demonstrated dispersion in the 200–500 nm wavelength range.

    关键词： PEMA,CAP,Band gap,UV laser irradiation

    更新于2025-09-23 15:21:01

  • Luminescence of Phosphate Glasses: P2O5-ZnO-BaF2-K2TeO3-Al2O3-Nb2O5 Doped with Sm3+ Ions for Display and Laser Material

    摘要： Luminescent phosphate glasses having the composition 40P2O5-30ZnO-20BaF2-3.8K2TeO3-1.2Al2O3-5Nb2O5 in mol.% doped with 3 9 103 ppm and 4 9 103 ppm Sm2O3 were successfully prepared by a melt-quenching technique. The investigated glasses were characterized by x-ray diffraction, UV–visible–NIR, absorption, emission, and ?uorescence lifetime analysis. The radiative properties were calculated using Judd–Ofelt (J–O) spectral intensity parameters for each of the glasses, which revealed the following trend: X2 > X4 > X6. The J–O intensity parameters were used to evaluate the spontaneous emission properties including branching ratios, transition probabilities, and radiative lifetime. The value of the optical energy band gap was found to decrease with an increase in Sm3+ content, which is explained on the basis of structural changes. The calculated stimulated emission cross-section studied was high, and increased from rSE; at 1.62 lm of glasses 3.81 9 10(cid:2)21 cm2 to 4.38 9 10(cid:2)21 cm2 with increasing Sm3+ ion concentration. The structure of the glasses was investigated by computing Internuclear (cid:3) and ?eld strength F( ) and measurement of Raman spectra.

    关键词： refractive index,UV–Vis–NIR,Judd–Ofelt analysis,emission cross-section,Raman spectra,Oxide glasses,density,optical energy gap

    更新于2025-09-23 15:21:01

  • Superior ferroelectric photovoltaic properties in Fe -modified (Pb,La) (Zr,Ti)O3 thin film by improving the remnant polarization and reducing the band gap

    摘要： In order to develop ferroelectric photovoltaic devices with high power conversion e?ciency, ferroelectric materials must have simultaneously large remnant polarization and narrow band gap so as to e?ciently separate photo-generated carriers and absorb more sunlight. Based on this idea, in this report, we introduce Fe3+ into Pb0·93La0·07(Zr0·6Ti0.4)0.9825O3 ferroelectric thin ?lm to increase the remnant polarization and decrease the band gap of the thin ?lm. In doing so, we prepare Fe3+ doping Pb0·93La0·07(Zr0·6Ti0.4)0.9825O3 thin-?lm based photovoltaic devices. The experimental results indicate that with increasing the Fe3+ amount, the remnant polarization of the ?lm ?rst improves to the maximum value of 50 μC/cm2 at the 4.8 mol% Fe3+ content and then reduces gradually, while the band gap continuously decreases. In addition, at a negative poling voltage, the device exhibits larger short-circuit current and open-circuit voltage in comparison with those obtained at the positive poling voltage, which is attributed to the depolarization electric ?eld originating from the remnant polarization of ferroelectric thin ?lms in the same direction as the built-in electric ?eld caused by the Schottky barrier. In this report, the most superior photovoltaic performances with the open-circuit voltage of as large as ?0.55 V and short-circuit current of as high as 0.4 μA/cm2 are obtained in the device with 4.8 mol% Fe3+ amount and at ?5 V poling voltage. This is on account of the improved sunlight absorbing properties and photo-generated carriers separation ability of the device. This work provides a novel idea for designing and preparing ferroelectric photovoltaic devices with high power conversion e?ciency.

    关键词： Fe3+ doping,Photovoltaic properties,Band gap,Remnant polarization,Ferroelectric thin ?lm

    更新于2025-09-23 15:21:01

  • Narrowing the Band Gap: The Key to High-Performance Organic Photovoltaics

    摘要： Organic photovoltaics (OPVs) have attracted considerable attention in the last two decades to overcome the terawatt energy challenge and serious environmental problems. During their early development, only wide-band-gap organic semiconductors were synthesized and employed as the active layer, mainly utilizing photons in the UV?visible region and yielding power conversion e?ciencies (PCEs) lower than 5%. Afterward, considerable e?orts were made to narrow the polymer donor band gap in order to utilize the infrared photons, which led to the enhancement of the PCE from 5% to 12% in about a decade. Since 2017, the study of narrow-band-gap non-fullerene acceptors helped usher in a new era in OPV research and boosted the achievable the PCE to 17% in only 3 years. In essence, the history of OPV development in the last 15 years can be summarized as an attempt to narrow the band gap of organic semiconductors and better position the energy levels. There are multiple bene?ts of a narrower band gap: (1) considerable infrared photons can be utilized, and as a result, the short-circuit current density can increase signi?cantly; (2) the energy o?set of the lowest unoccupied molecular orbital energy levels or highest occupied molecular orbital energy levels between the donor and acceptor can be reduced, which will reduce the open-circuit voltage loss by minimizing the loss caused by the donor/acceptor charge transfer state; (3) because of the unique molecular orbitals of organic semiconductors, the red-shifted absorption will induce high transmittance in the visible region, which is ideal for the rear subcells in tandem-junction OPVs and transparent OPVs.

    关键词： Organic photovoltaics,narrow-band-gap,non-fullerene acceptors,power conversion efficiencies,polymer donors

    更新于2025-09-23 15:21:01

  • The design and the performance of an ultrahigh vacuum 3He fridge-based scanning tunneling microscope with a double deck sample stage for in-situ tip treatment

    摘要： Scanning tunneling microscope (STM) is a powerful tool for studying the structural and electronic properties of materials at the atomic scale. The combination of low temperature and high magnetic field for STM and related spectroscopy techniques allows us to investigate the novel physical properties of materials at these extreme conditions with high energy resolution. Here, we present the construction and the performance of an ultrahigh vacuum 3He fridge-based STM system with a 7 Tesla superconducting magnet. It features a double deck sample stage on the STM head so we can clean the tip by field emission or prepare a spin-polarized tip in situ without removing the sample from the STM. It is also capable of in situ sample and tip exchange and preparation. The energy resolution of scanning tunneling spectroscopy at T = 310 mK is determined to be 400 mK by measuring the superconducting gap with a niobium tip on a gold surface. We demonstrate the performance of this STM system by imaging the bicollinear magnetic order of Fe1+xTe at T = 5 K

    关键词： Spin polarized scanning tunneling microscopy,Superconducting gap,Magnetic structure

    更新于2025-09-23 15:21:01

  • Textural and electro-optical study of a room temperature nematic liquid crystal 4ì?-pentyl-4-biphenylcarbonitrile doped with metal oxide nanowires in planar and in-plane switching cell configurations

    摘要： This work shows the doping effect of metal oxide nanowires (alumina nanowires) on the textural and electro-optical characteristics of nematic liquid crystal (5CB) in planar and in-plane switching (IPS) cell configurations. Results indicate the increase in nematic to isotropic phase transition temperature after doping in both planar and IPS cells. A decrease in threshold voltage in addition to increase in contrast ratio, birefringence, and band gap energy was observed after doping with alumina nanowires in both types of cells. Overall analysis shows that IPS cell configuration has more improved threshold voltage and contrast ratio in addition to decrease in birefringence and transmission intensity, as compared to planar cell configuration. No effect of cell configuration was observed on energy band gap and found same value for both planar and IPS cell configurations, as energy band gap is a material specific property.

    关键词： threshold voltage,Nematic liquid crystal,energy band gap,In-plane switching,nanowires

    更新于2025-09-23 15:21:01

  • The morphology regulation and plasmonic spectral properties of Au@AuAg yolk-shell nanorods with controlled interior gap

    摘要： Au@AuAg yolk-shell nanorods with tunable and uniform interior gap were synthesized through galvanic replacement reaction, where Au@Ag core-shell nanorods served as sacrificial templates and HAuCl4 solution served as reductant. The effects of HAuCl4, Ag shell thickness and aspect ratio (AR) of Au nanorods on the morphology of Au@AuAg yolk-shell nanorods had been investigated systemically. The results clearly indicated that AuAg alloy shell thickness of Au@AuAg yolk-shell nanorods could be increased from 3.6 to 10.0 nm by varying the amount of HAuCl4. Meanwhile, the shape of AuAg alloy shell could be tuned by changing the shape of Ag coating. With the increasing of Ag coating thickness, the interior gap could be finely tuned in the range from 2.6 to 8.1 nm. The uniformity of interior gap could be improved by increasing the AR of Au nanorods. All these tunable geometries can further affect the plasmonic spectral properties of Au@AuAg yolk-shell nanorods. Because of the appearance of interior gap, the longitudinal localized surface plasmon resonance (LSPR) peak of Au@AuAg yolk-shell nanorods was located between that of bare Au nanorods and Au@Ag core-shell nanorods without interior gap. The increase of outer AuAg shell thickness can weaken the coupling between the inner and outer surface of the AuAg shell and lead to the decrease of AR, so the transverse and longitudinal LSPR bands gather together. The decrease of Ag coating thickness can enhance the coupling between inner Au nanorod and outer AuAg shell, which results in the red shift of the longitudinal LSPR band. This paper provides a method for studying the plasmonic coupling between two metal surfaces with a metal layer or a dielectric layer, which is also a new approach for regulating the plasmonic spectral properties of bimetallic nanoparticles. The controllability of Au@AuAg yolk-shell nanorods in both the interior gap and outer alloy shells makes them have potential applications in biomedicine, catalysis, nanoreactors, and energy storage.

    关键词： interior gap,localized surface plasmon resonance,spectral properties,morphology regulation,Au@AuAg yolk-shell nanorods

    更新于2025-09-23 15:21:01

  • Two stage modelling of solar photovoltaic cells based on Sb2S3 absorber with three distinct buffer combinations

    摘要： Solar cell research has always been an attraction by virtue of its clean and green status. However, to overcome the implications of high cost and moderate efficiency, there has always been fierce competition to search alternative approach for designing efficient solar cells with optimal performance-cost ratio. Recently, antimony sulfide (Sb2S3) has received substantial attention as an absorber in thin film solar cells due to earth abundance, low cost, non-toxic property and high optical absorption. Still, its performance could not match Si based cells. In this work, we adopted two-stage simulation approach to design Sb2S3 absorber based heterojunction solar cell to enhance efficiency. Initial simulation for configuration optimization was done considering thickness, defect density, recombination (radiative, Auger) effect, carrier density of the Sb2S3 absorber layer. Buffer layer thickness and absorption coefficient optimization was taken up. Further, series and shunt resistance of the device as well as conduction band offset (CBO) at absorber/buffer interface was also optimized at initial stage only. In the next level of simulation, efficiency enhancement was achieved by optimizing optimal back contact metal work function, absorber layer band gap grading and temperature. The aforesaid two-stage optimization yielded efficiency ~24.81%, which is higher than conventional thin film solar cell. The optimal solar cell structure configuration, for Sb2S3 absorber solar cell, suggested a positive CBO of 0.26 eV (e.g.; ZnS buffer layer), a back contact metal work function of 5.1 eV (e.g.; Mo, Au) and band gap grading window ~1.31 to 1.62 eV.

    关键词： Conduction band offset,Sb2S3 solar cell,Work function,Band gap grading,Simulation

    更新于2025-09-23 15:21:01