Two new push-pull type second-order nonlinear optical (NLO) active isophorone-based alkoxysilane dyes with the same acceptor were synthesized and characterized. One silane (ICTES-HEMA) bears a chromophore with a hydroxyethyl methylamino donor and the other silane (ICTES-HMPP) is a bulkier analogue with a hydroxymethyl diphenylamino donor. Transparent, homogeneous films were prepared via the copolymerization of tetraalkoxysilane (TEOS) and different NLO silanes with the ratio of 5:1. The d(33) values obtained for the HEMA and HMPP films are 46.3 and 20.6 pm/V, respectively. Normalized UV-vis spectra reveal that the introduction of a diaryl group would help to prevent unfavorable organization of the chromophores. The reorientation dynamic stabilities of the samples were studied by second-harmonic generation (SHG) measurements, demonstrating that bulkier chromophores incorporated in sol-gel materials would not necessarily lead to higher stabilities over time. 相似文献
Four kinds of hydroxy-ended azobenzene-type chromophores containing different substituent groups as electron donor or electron acceptor were synthesized and further reacted with 3-isocyanatopropyltriethoxysilane (ICTES) to give alkoxysilane dyes via a urethane reaction. Following a sol-gel process of the alkoxysilane dyes, the inorganic-organic hybrid nonlinear optical (NLO) films were successfully prepared. Molecular structures of the resultant films were confirmed by elemental analysis, FTIR, and 1H NMR. The betaCT mu(g) values of the chromophores were evaluated by a solvatochromic method, and the second harmonic coefficients (d33) of the hybrid films were measured by in situ second harmonic generation (SHG) measurement. The hybrid films exhibited large optical nonlinearity and full transparency in the visible range. The effects of substituent group and position on betaCT mu(g) values of the chromophores and d33 values of the films were also discussed. 相似文献
The relaxation of poled nonlinear optical (NLO) chromophores in polymer films was characterized by infrared (i.r.) reflection-absorption spectroscopy. Both a guest-host system and a photocrosslinkable polymer system were investigated. Polymethylmethacrylate doped with either 2-methyl-4-nitroaniline or 4(4′-nitrophenylazo)aniline was studied. The photocrosslinkable polymer system, polyvinylcinnamate doped with 3-cinnamoyloxy-4-[4-(N,N-diethylamino)-2-cinnamoyloxy phenyl azo]nitrobenzene was also investigated. Doped NLO active molecules were aligned using the corona poling technique. i.r. spectra as a function of time were used to monitor the relaxation behavior of the oriented dyes after poling. Relaxation of NLO molecules was followed at various characteristic vibrational frequencies. The relaxation behavior of both systems were found to be consistent with those studied by the second harmonic generation technique. 相似文献
Summary: Self‐assessing polymer blends based on poly(ethylene terephthalate glycol) or linear low‐density polyethylene and small amounts (0.5–2% w/w) of chromogenic sensor dyes are prepared and investigated. The cyano‐substituted oligo(p‐phenylene vinylene) dyes employed in the study exhibit pronounced optical absorption changes upon self‐assembly, because of charge‐transfer interactions or conformation changes. The extent of dye aggregation (and therewith the optical absorption characteristics) in these blends is significantly influenced by exposure to external stimuli. Subjecting appropriately processed samples to either temperatures above their glass transition or mechanical deformation can significantly change the extent of aggregation, which in turn leads to a color change.
Mechano‐optical response of a 1.0% w/w LLDPE/C18‐RG blend film. Pristine films are orange due to aggregated dye molecules. Deformation leads to dispersion of the dye and irreversibly changes the color to yellow. 相似文献
The current study reports tailoring the electronic donor structures of organic dyes to modify their optical and nonlinear optical (NLO) response properties. Five (5) tri-phenyl amine (TPA) based Donor-π-Acceptor (D-π-A) organic dyes with the codes ICAA1 , ICAA2 , ICAA3 , ICAA4 , and ICAA5 were designed and investigated for their optical and NLO properties using quantum chemical methods. Optical and NLO properties of these dyes were studied by CAM-B3LYP method and 6-311G* basis set. The focus has been on the impact of adding secondary donors and shifting their substitutions at ortho (o), meta (m) and para (p) positions. Among all designed compounds, ICAA4 showed the highest amplitude of average third-order NLO polarizability <γ>, which is calculated to be 1316 × 10−36 esu. Time-dependent Density Functional Theory (TD-DFT) method was used to determine how a change in the position of the donor affected the excitation energy (Eg) and NLO response properties. The findings showed that changing the position of the secondary donor results in a red shift among absorption spectra as well as the increase in their NLO responses. Complete process of intramolecular charge transfer (ICT) has been investigated in terms of different optical parameters such as frontier molecular orbitals (FMOs), molecular electrostatic potentials (MEPs), transition density matrix (TDMs), density of states (DOS), electron density difference (EDD), and natural bond orbital (NBO) analysis. Our calculations for study of ICT process indicate that p-position of methoxy group performs better among all other positions and even it has better NLO response properties than the compound with three collective methoxy groups. The calculated Voc values of all designed molecules range from 1.09 to 1.30, all of them are positive while their ΔGinject is found to be in the range of −0.87 to −1.79 eV indicating their decent potential for photovoltaic applications. The studied optical, NLO and photovoltaic parameters illustrated that ICAA1 to ICAA5 are appropriate molecules not only for NLO applications but also for efficient photovoltaic purposes. 相似文献
Silicalite-1 films (thickness = 400 nm) supported on both sides of glass plates (SL/G) were prepared, and hemicyanine dyes (HC-n) with different alkyl chain lengths (n, n = 3, 6, 9, 12, 15, 18, 22, and 24) were included into the silicalite-1 films by dipping SL/Gs into each methanol solution of HC-n (1 mM) for 1 d. The included numbers of HC-n per channel (N(C)) generally decreased with increasing n; that is, they were 6.4, 23.1, 15.4, 8.2, 5.7, 3.5, 0.9, and 1.2 molecules per channel, respectively. The d(33) value gradually increased with increasing n but decreased when n > 18; that is, they were 1.12, 0.50, 2.25, 3.59, 4.99, 5.30, 1.71, and 2.57 pm V(-1), respectively. However, d(33)/N(C) progressively increased with increasing n. The d(31) values were approximately 100 times smaller than the corresponding d(33) values, and the average d(33)/d(31) ratio was 109, which is higher than those of Langmuir-Blodgett (LB) films and poled polymers of nonlinear optical (NLO) dyes, by approximately 2-5 and approximately 30-50 times, respectively. The estimated average tilted angle of the dyes with respect to the channel direction was 7.7 degrees, and the calculated average order parameter was 0.97, which is approximately 480 times higher than the values observed from poled polymers. The degree of uniform alignment (DUA) generally increased with increasing n. The progressive increase of both DUA and d(33)/N(C) with n is attributed to the increase in the tendency of HC-n to enter hydrophobic silicalite-1 channels with the hydrophobic alkyl chain first. A more than 134-fold increase in DUA was observed upon increasing n from 6 to 24. The DUA of HC-24 in the silicalite-1 film reached close to 1. Although the observed d(33) values were lower than those of the LB films of NLO dyes due to very small dye densities of the silicalite films, this methodology bears a great potential to be developed into the methods for preparing practically viable NLO films. 相似文献
The multilayer electroluminescent(EL) devices composed of vacuum-sublimed organic films are discussed with the aims of achieving high luminance and proposing an optical micro-cavity. For the former purpose, requirements for confinements of carriers and excitons within the thin emissive layer are shown by taking accounts of ionization potentials, electron affinities and excitation energies in organic thin films. Concerning the interference effect of emitted light, we show the variation in the intensity of emission and a strongly directional light from the micro-cavity. Second-order nonlinear optical(NLO) films are designed by preparing noncentrosymmetric LB multilayers composed of an pyrazine derivative with large hyperpolarizability and arachidic acid. Third-order nonlinear optical(NLO) films are proposed by using polyarylenevinylene films. In order to fabricate excellent third-order nonlinear optical(NLO) films, highly oriented polyarylenevinylene films are prepared by using a LB technique. 相似文献
Nonlinear optical (NLO) responses from organic dyes can be maximized when the dyes are aligned in appropriate manners in bulk materials. The use of restricted nanospaces provided by interlayer spacing of inorganic layered materials is a promising strategy for imposing suitable molecular alignments for NLO materials on dyes. The hybrid materials thus obtained exhibit salient NLO responses owing to the improved molecular orientation. In some cases, extension of the π‐electron system as a consequence of improved molecular planarity, obtained by the intercalation of a dye into the 2‐dimensional interlayer space of an inorganic layered material, is also observed as a factor that enhances NLO responses of chromophores at the molecular level. This review focuses on recent progress in the strategies for controlling the molecular orientation of NLO‐phores by employing clay minerals, which are one of the typical inorganic layered materials. In addition, development of a means for fabricating composites that satisfy the properties of an optical material, such as a sufficient size and thickness, a flat surface, and low light‐scattering characteristics is required to utilize the superior NLO properties observed for clay/dye hybrid materials for practical applications. A novel means for obtaining such a hybrid material is also outlined. 相似文献
Typical asymmetric donor-π-bridge-acceptor(D-π-A) zinc porphyrin dyes have been synthesized, and further modified by reacting the ethynyl groups of them with click reagent through a formal [2+2] click reaction. The electronic interaction between the push and pull electronic groups and the click reaction process were investigated by UV-Vis absorption spectroscopy. The nonlinear optical(NLO) properties of the dyes were studied by the Z-scan technique and clearly reverse saturable absorption to saturable absorption(RSA-SA) transition could be observed through click reaction of the dyes with TCNE. Furthermore, the photovoltaic properties of these porphyrin dyes were reaso- nably explained by the J-V curve fitting based on the equivalent-circuit model as well as the comparison between the absorption and incident-photon-to-current-conversion efficiency(IPCE) spectra. Besides, these dyes with different donors or acceptors could self-assembly into different microstructures by phase transfer methodology. 相似文献
Interpenetrating polymer networks (IPNs) based on polyurethane and polyacrylate-containing 4-(4'-nitrophenylazo) aniline chromophore groups were synthesized and characterized by infrared spectra, gel content and differential scanning calorimetry. Thin, transparent films of the IPNs were prepared by spin-coating, followed by thermal curing and corona poling. The poled IPN film shows very good optical properties and exhibits only one glass transition temperature. The second-order nonlinear optical (NLO) properties of the poled film were studied by visible light absorbance measurement according to one-dimensional rigid oriented gas model. The second-order nonlinear optical polarizability can reach 10-7 e.s.u. The poled IPN film of defined composition showed a good temporal stability of NLO properties at 120°C for more than 160 hr. 相似文献
Several near-infrared (NIR) fluorescent dyes based on aminocyanine have been designed, synthesized, and used for preparation of NIR fluorescent microspheres. Their spectral properties and pH-dependent optical characteristics were investigated. It was found that different substitution at the central position of the dyes led to diverse optical properties, with especially large effects on their spectroscopic properties. Spectroscopic responses of the fluorescent dyes to changes of pH were different. Under acidic conditions, the wavelengths of maximum absorption of the N-substituted cyanine dyes were clearly red shifted. Dyes with an N-substituted piperazidine ring were the most sensitive. The fluorescent microspheres retained the properties of the parent dyes, making them suitable for applications in biological studies. 相似文献