We numerically study plasmonic solar cells in which a square periodic array of core–shell Ag@SiO2 nanospheres (NSs) are placed on top of the indium tin oxide (ITO) layer using a 3D finite-difference time-domain (FDTD) method. We investigate the influence of various parameters such as the periodicity of the array, the Ag core diameter, the active layer thickness, the shell thickness, and the refractive index of the shell materials on the optical performance of the organic solar cells (OSC). Our results show that the optimal periodicity of the array of NSs is dependent on the size of Ag core NSs in order to maximize optical absorption in the active layer. A very thin active layer (<70 nm) and an ultrathin (<5 nm) SiO2 shell are needed in order to obtain the highest optical absorption enhancement. Strong electric field localization is observed around the plasmonic core–shell nanoparticles as a result of localized surface plasmon resonance (LSPR) excited by Ag NSs with and without silica shell. Embedding 50 nm Ag NSs with 1-nm-thick SiO2 shell thickness on top of ITO leads to an enhanced intrinsic optical absorption in a 40-nm-thick poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) active layer by 24.7% relative to that without the NSs. The use of 1-nm-thick ZnO shell instead of SiO2 leads to an enhanced intrinsic absorption in a 40-nm-thick P3HT:PCBM active layer by 27%.
相似文献The optical properties of a novel nanostructure consisting of a hexagonal array of aligned vertically three-layered metal-dielectric-metal nanodisks on a silver film are theoretically studied through the finite-difference time-domain method. The novel nanostructure exhibits three obvious optical transmission bands due to the excitation of subradiant plasmon modes, superradiant plasmon modes, and Fano resonances. Surface plasmon polaritons of the underlying Ag film also play a significant role on these three optical transmission bands via coupling with localized surface plasmons of nanodisk pairs. Moreover, the nanostructure also exhibits a good tunability of optical response by modifying the sizes of cylinders, the thickness of underlying metal film, and the dielectric constant of middle layer. These results demonstrate the nanostructure with great advantages in optical sensors and filters.
相似文献We demonstrate plasmon coupling phenomenon between equivalent (homodimer) and non-equivalent (heterodimer) spherical shape noble metal nanoparticle (Ag, Au and Al). A systematic comparison of surface plasmon resonance (SPR) and extinction properties of various configurations (monomer, homodimer and heterodimer) has been investigated to observe the effect of compositional asymmetry. Numerical simulation has been done by using discrete dipole approximation method to study the optical properties of plasmonically coupled metal nanoparticles (MNPs). Plasmon coupling between similar nanoparticles allows only higher wavelength bonding plasmon mode while both the plasmon modes lower wavelength antibonding mode as well as higher wavelength bonding mode in the case of heterodimer. Au monomer of radius 50 nm shows resonance peak at 518 nm while plasmon coupling between Au-Au homodimer results in a spectral red shift around 609 nm. Au-Ag plasmonic heterodimer (radius 50 nm) reveals two resonant modes corresponding to higher energy antibonding mode (422 nm) as well as lower energy bonding mode (533 nm). Further, we have shown that interparticle edge-to-edge separation is the most significant parameter affecting the surface plasmon resonances of MNPs. As the inter particle separation decreases, resonance wavelength shows red spectral shift which is maximum for the touching condition. It is shown that plasmon coupling is a reliable strategy to tune the SPR.
相似文献Noble metals, especially Ag and Au nanostructures, have unique and adjustable optical attributes in terms of surface plasmon resonance. In this research, the effect of Ag and Au nanoparticles with spherical and rod shapes on the light extraction efficiency and the FWHM of OLED structures was investigated using the finite difference time domain (FDTD) method. The simulation results displayed that by changing the shape and size of Ag and Au nanostructures, the emission wavelength can be adjusted, and the FWHM can be reduced. The presence of Ag and Au nanoparticles in the OLEDs showed a blue and red shift of the emission wavelength, respectively. Also, the Ag and Au nanorods caused a significant reduction in the FWHM and a shift to the longer wavelengths in the structures. The structures containing Ag nanorods showed the narrowest FWHM and longer emission wavelength than the other structures.
相似文献The angle-variable tunable optical filter was strictly fabricated by two strategies of nanoimprint-coupled metal nanopatterning with improved cost-effectiveness and accessibility. The tunable optical properties and the performances of two strategies were experimentally examined and turned out to be well matched to numerical results. Tunable properties are obtained by three factors: size of fabricated Ag nanodisks, incident illumination angle, and fabrication strategies. The resonant extinction peak shifts were identified to show a large increase along with the increase in fabricated Ag disk size and increase in the incidence angle of illumination. When comparing a fabrication strategy, it was confirmed that the sample fabricated by the strip-off method has better stability on color changes with a consistent dependency on the incident angle. The presented strategies of fabrication are technically viable for obtaining well-defined plasmonic nanostructures so that it has the feasibility to apply for fascinating optical applications including display or tunable optical filters.
相似文献In the present report, we focused on the detail study of the optical properties and structural characterization of the Ag NPs for the nanobioconjugate analysis and detection of the conformational structural change of the Hb. The detail optical and structural analysis of Ag NPs has been studied from UV–Vis absorption, emission spectrum, XRD, and HRTEM study. The proteins/Hb are attached immediately onto Ag NPs surface when NPs touch the biological fluids, forming protein corona (PC), which gives their biological identity. The NPs-PC bioconjugate is, more specifically, the true identity of NPs in the physiological world. The adsorption of Hb with Ag NP surfaces has been studied by monitoring the soret band and tryptophan band of Hb. The dynamics of the Hb adsorption on the Ag NPs showed the time constant of surface binding t1?=?5.79 min and 10.23 min and surface reorganization t2?=?500 min and 251.75 min with the use of small and large concentrations of Ag NPs, respectively. The absorption peak shape and size around the wavelength, λ ≈ 406.2 nm of the bioconjugate has been examined by Gaussian and Lorentz curve fitting analysis. The bioconjugate along with the PC formation has been analyzed by HRTEM images and DLS observations. The tertiary deformation of Hb and energy transfer efficiency connecting Ag NPs and Hb are discussed from the emission-quenching phenomenon. The change of the secondary structural elements (α-helix, β-sheets, intermolecular aggregates, intramolecular aggregates) of the bioconjugate has been analyzed from FTIR spectrum.
相似文献Diamagnetic TeO2-PbO-B2O3 glasses were melt-quenching fabricated and characterized for Fe3O4/Ag nanoparticles doping through radio-frequency sputtering and thermal treatment techniques. The surface plasmon resonance influenced structure, composition, optical, and magneto optical properties of Fe3O4/Ag doped glasses were investigated through XRD, SEM, XPS analysis, and Faraday rotation measurement. The optimized sputtering and thermal conditions Fe3O4 and Ag nanoparticles were obtained. Under the optimized conditions, a great enhancement of Faraday rotation, thermal property, and big UV cutoff red-shift due to the excited surface plasma’s resonance effect was achieved in diamagnetic glass.
相似文献This paper mainly studies the influence of multilayer hyperbolic metamaterials (HMMs) with different structural parameters on the intensity of spontaneous radiation of quantum wells, thereby improving the coupling efficiency of incident electromagnetic waves and free electrons on metal nano-surfaces. In this paper, numerical simulations of visible light bands of 450–700 nm of Ag, Au, and Cu thin films are performed. The local field enhancements of multilayer HMMs with different shapes are compared, and it is found that circle Ag/Si multilayer HMMs have stronger field enhancement effects than other structures. At the same time, Purcell analysis was performed by changing various parameters of multilayer HMMs. It is found that the thickness of the metal/dielectric layer, the distance between the dipole and the HMMs, and the length of the multilayer HMMs change the intensity of the plasmon resonance radiation and have a great impact on the position of the resonance wavelength.
相似文献In this paper, we have inspected the optical characteristics of one-dimensional periodic structure (1DPS) of TiO2 and MgF2 dielectric materials with defect layer of liquid crystal (LC) sandwiched with two silver layers, i.e., (TiO2|MgF2)3|Ag|LC|Ag|(TiO2/MgF2)3 using transfer matrix method (TMM). The optical tunable properties of considered periodic structures investigated at different incident angles and temperatures for TE and TM modes. Our study shows that absorption peak of 1DPS varies with incident angle and temperature. The defect layer (Ag-LC-Ag), sandwiched LC within two metallic (Ag) layers, exhibits the surface plasmon waves at the metal LC interfaces. The effect of surface plasmon waves can be better understand through the optical sensing property of such defect periodic structure. The detailed study concludes that such a type of one-dimensional periodic structure (1DPS) may be useful to design a tunable sensor and monochromatic filter.
相似文献Significance and Impact of Study
Although the synthesis, structural characteristics and biofunction of silver nanoparticles are well understood, their application in antimicrobial therapy is still at its infancy as only a small number of microorganisms are tested to be sensitive to nanoparticles. A thorough knowledge of the mode of interaction of nanoparticles with bacteria at subcellular level is mandatory for any clinical application. The present study deals with the interactions of Ag–SiO2NC with the cell wall integrity, metabolism and genetic stability of Pseudomonas aeruginosa, which would contribute substantially in strengthening the therapeutic applications of silver nanoparticles. 相似文献Time-resolved polarization-dependent transient absorption has been used to study the plasmonicity of the optical transitions of Ag nanoparticles and nanoclusters. The lack of a measureable polarization anisotropy in the nanoparticles is indicative of the ultrafast electron-electron scattering while the anisotropy with a depolarization timescale of 500 fs observed in the nanoclusters indicates the excitation of a non-plasmonic state. The short lifetime of the anisotropy is a measure of electronic coupling between nearly degenerate states and is thus proposed as a sensitive measurement of the plasmonic content of the optical transitions of nanoclusters.
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