The “far‐field” effect of metal nanoparticles (NPs), when chromophores localized nearby metal NPs (typically the distance >λ/10), is an important optical effect to enhance emission in photoluminescence. The far‐field effect originates mainly from the interaction between origin emission and mirror‐reflected emission, resulting in the increased irradiative rate of chromophores on the mirror‐type substrate. Here, the far‐field effect is used to improve emission efficiency of polymer light‐emitting diodes (PLEDs). A universal performance improvement is achieved for the full visible light (red, green, blue) PLEDs, utilizing gold (Au) NPs to modify the indium tin oxide (ITO) substrates; this is shown by experimental and theoretical simulation to mainly come from the far‐field effect. The optimized distance, between the NPs and chromophores with visible light emission ranging from 400 to 700 nm, is 80–120 nm. Thus the scope of the far‐field may overlap the light‐emitting profile very well to enhance the efficiency of optoelectronic devices. The 30–40% enhancement is obtained for different color‐emitting materials through distance optimization. The far‐field effect is demonstrated to enhance device performance for materials in the full‐visible spectral range, which extends the optoelectric applications of Au NPs. 相似文献
Ordered Sr2CrReO6 has been synthesized recently. It is measured to be ferrimagnetic semiconductor, in contrary to the previous reports of metallic properties. To solve the discrepancy, we have investigated the compound by using the density functional theory. The semiconducting behavior is reproduced by including the electron correlation and spin–orbit coupling simultaneously. The calculated band gap is 0.22 eV, close to the experimental value of 0.21 eV. A large orbital moment of 0.69µB is found for Re, which is caused by the Coulomb‐enhanced spin–orbit coupling. By applying pressure, a semiconductor to half‐metal transition is observed through 5% volume compression.
In this paper, we investigate the optical properties of
the double-layer metal films perforated with single apertures by
analysing the coupling of localized surface plasmon polaritons (LSPPs).
It is found that the amplitude and the wavelength of transmission
peak in such a structure can be adjusted by changing the
longitudinal interval D between two films and the lateral
displacements d_{x} and d_{y} which are parallel and
perpendicular to the polarization direction of incident light,
respectively. The variation of longitudinal interval D results in
the redshift of transmission peak due to the change of coupling
strength of LSPPs near the single apertures. The amplitude of
transmission peak decreases with the increase of d_{y} and is less
than that in the case of d_{x}, which originates from the
difference in coupling manner between LSPPs and the localized
natures of LSPPs. 相似文献
Optical sensors based on surface plasmons have attracted much attention over the past decades owing to the wealth of applications in bio‐ and chemical and gas sensing. In surface plasmon resonance sensors, a single metal layer is commonly used, but its resolution is limited because of broad resonances. In this context, we have developed a sensor chip based on a stack of metals and a dielectric, e.g. a metal‐insulator‐metal structure, consisting of a thick insulator layer sandwiched by metal layers, that exhibits a sharp resonance due to the excitation of surface plasmon polaritons hybrid modes. We have performed both experiments and theoretical simulations to estimate the enhancement of the sensitivity of such a structure. By changing the refractive index of an aqueous solution of glucose on top of the sensor chip, we found that the use of a metal‐insulator‐metal structure improves the figure of merit of the sensor 7.5 times compared to that of a conventional surface plasmon resonance sensor chip. 相似文献
The fluorescence characteristics of 8-hydroxyquinoline derivative complexes of A1(III), Ga(III), In(III), Zn(II), and Be(II) in differently charged micellar media are reported. For most of the chelates studied, large increases are observed in micellar media compared with those obtained in hydroorganic solvents. However, some exceptions are observed, of which the low fluorescence of Zn(II) chelates in anionic sodium lauryl sulfate media is the most noticeable. 相似文献
The results of first principles electronic structure calculations for the metallic rutile and the insulating monoclinic phase of vanadium dioxide are presented. In addition, the insulating phase is investigated for the first time. The density functional calculations allow for a consistent understanding of all three phases. In the rutile phase metallic conductivity is carried by metal orbitals, which fall into the one‐dimensional band, and the isotropically dispersing bands. Hybridization of both types of bands is weak. In the phase splitting of the band due to metal‐metal dimerization and upshift of the bands due to increased p‐d overlap lead to an effective separation of both types of bands. Despite incomplete opening of the optical band gap due to the shortcomings of the local density approximation, the metal‐insulator transition can be understood as a Peierls‐like instability of the band in an embedding background of electrons. In the phase, the metal‐insulator transition arises as a combined embedded Peierls‐like and antiferromagnetic instability. The results for VO2 fit into the general scenario of an instability of the rutile‐type transition‐metal dioxides at the beginning of the d series towards dimerization or antiferromagnetic ordering within the characteristic metal chains. This scenario was successfully applied before to MoO2 and NbO2. In the compounds, the and bands can be completely separated, which leads to the observed metal‐insulator transitions. 相似文献
In this paper,we reveal that the enhanced transmission through a perforated metal film can be further boosted up by a V-shaped nanoslit,which consists of two connected oblique slits.The maximum transmission at resonance can be enhanced significantly by 71.5%in comparison with the corresponding vertical slit with the same exit width.The value and position of transmission resonance peak strongly depend on the apex angle of the V-shaped slit.The optimum apex angle,at which the transmission is maximal,is sensitive to the slit width.Such phenomena can be well explained by a concrete picture in which the incident wave drives free electrons on the slit walls.Moreover,we also simply analyze the splitting of the transmission peak in the symmetry broken V-shaped slit,originating from the resonances of different parts of the V-shaped slit.We expect that our findings will be used to design the nanoscale light sources based on the metal nanoslit structures. 相似文献
Abstract Charge transfer (CT) complexes of p-benzoquinone derivatives with Indolyldiene aniline derivatives have been prepared and investigated by Elemental analysis, IR, 1H-NMR and electronic absorption spectroscopy. The spectral changes revealed that acidic acceptors form complexes with π - π? electronic interaction and proton transfer while non-acidic acceptors yield complexes having π - π transition only. The formation of 1:2 (D:A) complexes is also ascertained. The ionization potential and electron affinity are determined from the electronic absorption spectra for both the donors and acceptors respectivily. 相似文献