Fig 3
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A novel organic photorefractive composite system is presented consisting of the amorphous multifunctional low-molar mass compound DR1-DCTA, doped with C
60
as sensitizer and diisooctyl phthalate (DOP) as plasticizer. DR1-DCTA, a carbazole substituted triphenylamine with a covalently attached nonlinear optical azo chromophore unit has been synthesiz...
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... °C. melted composite by means of capillary forces. The photoref- ractive mixture of 6, DOP (71528 wt%) as well as 1 wt% of Nevertheless, decomposition of the composite under the con- ditions applied for device preparation (180 °C ) can be fullerene C 60 (allowing for a more efficient photogeneration at the laser wavelength of 670 nm) is shown in Fig. 3. Due to its excluded. Fig. 5 shows the absorption spectrum of 6 in dioxane low melt viscosity, this low molar mass composite is easily drawn between the glass layers of the ITO-cell yielding homo- solution. The bands at l=310 nm and 340 nm belong to the absorption of the aromatic triphenylamine core. The maximum geneous films of ...
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Luminescence piezochromism have risen to prominence in recent decades, while most are limited in pure organic compound and fluorescence. In this work, a Cu3Pz3 (Cu3, Pz: pyrazolate) cyclic trinuclear complex (CTC) with two different crystalline polymorphs, namely 1a and 1b, was synthesized. The CTC consists two functional moieties: carbazole (Cz) c...
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... According to similar literature methods [40,41], monomers PhCz-2Cz (3) and TPA-2Cz (3′) were synthesized by a three-step reaction sequence (Scheme 1). The first step is to prepare N-(4-methoxyphenyl)carbazole (1) and (4-methoxyphenyl)diphenylamine (1′) using a coppercatalyzed Ullmann C-N coupling reaction between 4-iodoanisole with carbazole and diphenylamine, respectively. ...
... According to similar literature methods [40,41], monomers PhCz-2Cz (3) and TPA-2Cz (3′) were synthesized by a three-step reaction sequence (Scheme 1). The first step is to prepare N-(4-methoxyphenyl)carbazole (1) and (4-methoxyphenyl)diphenylamine (1′) using a coppercatalyzed Ullmann C-N coupling reaction between 4-iodoanisole with carbazole and diphenylamine, respectively. ...
Two carbazole end-capped monomers containing triphenylamine or N-phenylcarbazole as an interior core, namely 4,4′-di(carbazol-9-yl)-4″-methoxytriphenylamine (TPA-2Cz) and 3,6-di(carbazol-9-yl)-N-(4-methoxyphenyl)carbazole (PhCz-2Cz), were prepared by a well-known chemistry from readily available reagents. The electrochemistry and electropolymerization of these two monomers were investigated and compared with those of structurally similar analogs with tert-butyl groups attaching on the active sites of the end-capped carbazole units. The polymeric films were built onto ITO/glass surface by repetitive cyclic voltammetry (CV) scanning of the monomer solutions containing an electrolyte. The electro-generated polycarbazole films exhibited high redox-activity and strong color changes upon electro-oxidation, which can be switched by potential modulation. The remarkable electrochromic behavior of the film was clearly interpreted on the basis of spectroelectrochemical studies, and the electrochromic stability was evaluated by the electrochromic switching studies.
Recently, combination of porphyrin and polyoxometalates in various interaction modes proved to be the basis of opening new avenues in the field of optical materials. Herein, two new looped covalently bonded Anderson-type polyoxometalate-porphyrin hybrids, having molecular formulae as [(C4H9)4N]6[{C42H26N6(CO)2(NH)2C2(OCH2)6(MnMo6O18)2{(OCH2)6C2(NH)2(CO)2N6H26C42}]⋅2CH3CN (denoted [email protected]), [(C4H9)4N]6[{C44H28N4(CO)2(NH)2C2(OCH2)6}(MnMo6O18)2{(OCH2)6C2(NH)2(CO)2N4H28C44}] (denoted [email protected]), were synthesized by the reaction of [N(C4H9)4]4[α-Mo8O26], Mn(OAc)3∙2H2O with two porphyrins 4,4'-(10,15-di(pyridin-4-yl)porphyrin-5,20-diyl)bis(N-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)benzamide) (denoted [email protected]) and 4,4'-(10,15-diphenylporphyrin-5,20-diyl)bis(N-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)benzamide) (denoted [email protected]), respectively. The hybrids were clearly characterized by spectroscopic (NMR, 2D-NOESY NMR, FT-IR, UV-visible, fluorescence) techniques, elemental analyses and electron spray ionization mass spectrometry (ESI-MS) techniques. Prominently, remarkable enhancement of the non-linearity of the hybrid [email protected] (consisting of two POM moieties and two phenyl-containing porphyrin moieties) over its corresponding porphyrin precursor was observed under laser irradiation indicating that integration of electron-accepting POM moiety and electron-donating Di-TPP moiety can significantly enhance the NLO response of the porphyrins, while [email protected] (consisting of two POM moieties and two pyridyl-containing porphyrin moieties) has larger molecular second hyperpolarizability than [email protected], the contribution per porphyrin moiety and POM moiety in [email protected] is slightly smaller than that in [email protected] due to the offset effect in a certain degree because both the POM moieties and the pyridyl groups have electron-withdrawing characters. It is also found that the HOMO-LUMO gap (Eg) values of the hybrids that were obtained according to the absorption edges of UV-vis. spectra decreased in an order of Eg([email protected]) > Eg([email protected]) > Eg([email protected]) > Eg([email protected]), whilst, the molecular second hyperpolarizability γ increased as follows γ([email protected]) ˂ γ([email protected]) ˂ γ([email protected]) ˂ γ([email protected]). Meantime, it is also found that fluorescence intensity was decreased by 90 %, 85% for the hybrids [email protected], [email protected], respectively, as compared to their porphyrin precursor molecules [email protected] and [email protected], respectively, due to energy and/or charge transfer from porphyrin moieties to Anderson type polyoxometalate moieties.
A series of amorphous molecules that possess both photoconductive and electro-optic properties was synthesized in order to investigate photorefractive properties of bifunctional organic-glasses. Diethylaminobenzaldehyde-diphenylhydrazone was covalently attached to 5-(4-diethylamino-benzylidene)-1,3-dimethylpyrimidine-2,4,6-trione through a flexible alkyl chain (3, 4, 5, 6 and 10 carbons) containing two ether linkages. The longer linkage not only lowered the glass transition temperature (T_g) of the molecules, but also allowed faster orientation of the chromophore. To examine the photorefractive properties, a 50 ?m-thick film was prepared from the mixture of a bifunctional molecule, butyl benzyl phthalate, and C_{60}. The photoconductivity of this composite was as high as 8.01\;{\times}\;10^{-12} S/cm at 60 V/ ?m, and the maximum diffraction efficiency ( {\eta}_{max}) of 50 ?m-thick film was about 5% at 80 V/ ?m.
Organic/polymer photorefractive materials have great potential in many areas such as message transmission, message storage and information processing due to their versatility in structural design, simplicity in sample preparation, highestfigure-of-merit and comprehensive performance. In the paper, several typical applications of photorefractive behavior were illustrated for organic photorefractive materials, and the current attentive research on their composition characteristic and performance were reviewed. Then the recent research progress at the design and preparation of organic photorefractive materials were also reviewed individually. Moreover, the existing bottle-neck problems about photorefractive material system were analyzed. Finally, their application and development in future were forecasted.
Methacrylate monomers containing a carbazole fragment and a chromophoric azophenyl sulfonyl group were synthesized, being characterized as definite chemical species and as potential intermediates for photorefractive applications. Quantum chemical calculations were carried out to get values of dipole moments, polarizabilities and hyperpolarizabilities. These values were used to calculate figure of merit (FOM) of the monomers, which indicated a contribution of linear and nonlinear optical effects to photorefractive phenomena. It was found that in the monomers in question the linear optical effect contribution prevailed over nonlinear one.
Various push-pull azobenzene molecular derivatives showing glassy properties have been processed as thin monomeric amorphous films using spin-coating and thermal evaporation in vacuum. This latter deposition technique yielded homogenous thin films whose surface RMS roughness has been found less than 0.3 Å. Contrarily to spin-coated films requiring external poling for SHG emission, evaporated thin films have proved spontaneously active in second harmonic generation (SHG) when probing at 1.907 μm. Heating above Tg and continuous illumination with an Ar+ laser in the sample absorption maximum band caused dramatic and irreversible disappearance of the spontaneous SHG signal. Applying an external static electric field by using corona discharge induced SHG reversible modulation whose sign has been tuned by changing the bias from positive to negative. Films obtained by vacuum evaporation under a 4 kV voltage underwent considerable morphology changes characterized by the formation of stable 250 nm high nanoclusters evidenced by AFM imaging. The dramatic decrease in SHG has been attributed to the formed nanopillars whose growth depends apparently on the substrate polarization state and must obey a centrosymmetric organization.
A new bifunctional photorefractive active succinate (TPD-2DCVA) consisting of a tetraphenyldiaminobiphenyl (TPD) unit and 4-dicyanovinylaniline (DCVA) moieties was prepared, which forms stable molecular glass. The glass-transition temperatures (T-g's) of TPD-2DCVA-based composites were efficiently controlled by the doping of small amount of plasticizers. The compound possesses a high photoconductivity of 2.1 x 10(-9) cm Omega(-1) W-1 at 50 V mu m(-1). A gain coefficient of 56.7 cm(-1) at electric field of 56 V mu m(-1) was achieved. Fast response times of 29-37 ms were also obtained at low electric fields for these composites.
The two succinates containing tetraphenyldiaminobiphenyl (TPD) or tetraphenylphenylenediamine (PDA) unit as a charge transporting moiety and dicyanovinylaniline unit as an electro-optical (EO) chromophore were prepared. Synthesized succinates (TPD-2DCVA, and PDA-2DCVA) show glass transition and form stable amorphous molecular glass at room temperature without a polymer binder or a plasticizer. TPD-2DCVA doped with 0.2 wt% of fullerene shows 28% of diffraction efficiency, and 110 cm-1 of coupling gain at 55V/μm, while PDA-2DCVA shows no photorefractivity at room temperature probably due to the difficulty of orientation of EO moiety because of higher glass transition temperature. The diffraction efficiency of TPD-2DCVA significantly increased by the addition of 0.5 wt % of PDA-2DCVA, which might be due to the increase of trap density. Fast response, observed for TPD-2DCVA, was ascribed to the large photoconductivity.
A new series of 2,8-disubstituted dibenzofuran derivatives (dbf) have been synthesized via palladium-catalyzed coupling reactions of 2,8-diiododibenzofuran and diarylamines. These compounds are amorphous with a glass transition temperature ranging from 65 to 193 °C. The emission colors of the materials vary from blue to bluish green. Two types of double-layer organic light-emitting diodes (OLEDs) were fabricated using these compounds as hole-transporting/emitting layers and TPBI or Alq3 as an electron-transporting layer: (I) ITO/dbf/TPBI/Mg:Ag and (II) ITO/dbf/Alq3/Mg:Ag (TPBI = 1,3,5-tris(N-phenylbenzimidazol-2-yl)-benzene; Alq3 = tris(8-hydroxyquinoline)aluminum). In general, type I and type II devices have excitons confined in the hole-transporting and the electron-transporting layers, respectively. Some blue-emitting devices of type I have promising performance.
