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The poly(p-phenylenevinylene)/polyurethane (PPV/PU) composite films obtained from water-borne PU system with PPV precursor (PrecPPV) were investigated. UV-VIS absorption, photoluminescence (PL), thermoluminescence (TL) spectra and...
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The poly(p-phenylenevinylene)/polyurethane (PPV/PU) composite films obtained from water-borne PU system with PPV precursor (PrecPPV) were investigated. UV-VIS absorption, photoluminescence (PL), thermoluminescence (TL) spectra and dynamic mechanical analysis (DMA) results of pure PPV and its composite are reported and analysed. The conversion of the PrecPPV/PU into PPV/PU composite was confirmed also by mean of dielectric spectroscopy. It was concluded from the UV-VIS absorption and PL spectra at room temperature that the conjugation length of the PPV chains in this composite and in pure PPV is similar. In the PL spectra at low temperatures positions of the peaks are the same in the pure PPV and in the composite. Upon cooling all peaks shift towards longer wavelengths and change their relative intensities. The TL spectra show that in these materials relatively shallow traps dominate, yielding TL maximum at ca. 70 K. The composite films cast from water suspension are flexible in contrast to pure PPV which forms rigid film. In DMA it is reflected by lower values of the storage modulus E' and of the amplitude of tandelta in the composites compared to pure PPV film.
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A competitive approach to obtain functionalized polymers is described in this presentation. It consists on the use functionalized sol-gel systems, known to form excellent optical quality thin films. Usually these systems suffer of...
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A competitive approach to obtain functionalized polymers is described in this presentation. It consists on the use functionalized sol-gel systems, known to form excellent optical quality thin films. Usually these systems suffer of the low density of active chromophores. In this approach the chromophore concentration is significantly higher. The active NLO chromophores are oriented by corona poling technique. The kinetics of poling was studied by the spectrophotometric method.
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A new method for the characterization of the kinetics of rotational mobility of chromophores embedded in a polymer matrix is proposed. The method is applied and checked with two different systems consisting of a solid solution of ...
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A new method for the characterization of the kinetics of rotational mobility of chromophores embedded in a polymer matrix is proposed. The method is applied and checked with two different systems consisting of a solid solution of Disperse Red 1 chromophore (DR1) either in PMMA or in bisphenol A thermally reticulating resine.
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Paper presents the absorption and photoluminescence of 7-TFM, 6-F, 6-CN, 6-TBu and 6-COOEt derivatives of 1-phenyl-3-methyl-1H-Pyrazolo[3,4-b]quinoline (MPPQ). The measured spectra are compared with the results of the quantum chem...
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Paper presents the absorption and photoluminescence of 7-TFM, 6-F, 6-CN, 6-TBu and 6-COOEt derivatives of 1-phenyl-3-methyl-1H-Pyrazolo[3,4-b]quinoline (MPPQ). The measured spectra are compared with the results of the quantum chemical calculations performed by means of the semi-empirical methods (AMI or PM3) that have been applied either to the equilibrium molecular conformations in vacuo (T = 0 K) or combined with the MID simulations (T 300 K). The photoluminescent spectra of MPPQ dyes are highly solvatochromic. The emission bands broaden and shift to the red with the increasing of solvent polarity, indicating thus a substantial dipole moment of the excited states. According to the quantum chemical analysis the reason for the strong solvatochromism of MPPQ dyes is related with intramolecular charge transfer (ICT) state. Due to the large dipole moment in the twisted geometry the ICT state is believed to become the lowest excited state in a strongly polar environment. This would explain a considerable solvatochromic shift in the highly polar solvents observed for all MPPQ dyes in the experiment. Such hypothesis is supported by the semi-empirical quantum chemical evaluations. (c) 2008 Elsevier B.V. All rights reserved.
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Synthesis of new PVK and 1H-pyrazolo[3,4-b]quinoline based copolymers for electro-optic applications is described. Both copolymers are soluble and can be processed into thin films. A single layer OLED structure was fabricated and ...
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Synthesis of new PVK and 1H-pyrazolo[3,4-b]quinoline based copolymers for electro-optic applications is described. Both copolymers are soluble and can be processed into thin films. A single layer OLED structure was fabricated and a blue light emission was observed. Although devices were not optimized, the "turn-on bias voltage was relatively low, ca. 12 V.
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In this paper we present the first results concerning the Third Harmonic Generation (THG) for thin films of functionalized alkynyl ruthenium based chromophores. This approach allowed us to determine the electronic contribution of ...
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In this paper we present the first results concerning the Third Harmonic Generation (THG) for thin films of functionalized alkynyl ruthenium based chromophores. This approach allowed us to determine the electronic contribution of the third-order nonlinear optical susceptibility chi(3)(elec) of these chromophores and to investigate three theoretical models (Reintjes model, Kubodera and Kobayashi model, and Kajzar and Messier model) as valuable approximations for transcribing the observed results. The highest value of third-order susceptibility found for studied compounds was equal to chi(3)(elec) = 3.0x10-(20) m(2)/V-2 e (at the wavelength lambda(omega)= 1064 nm, pulse duration 15 ps, average energy 1.6 mJ per pulse, pulse repetition frequency 10 Hz).
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In this paper the synthesis of some new chromophores which could be used in polymer/organic LED fabrication are presented. All of them are pyrazoloquinoline (PAQ) derivatives. Their emission proper-ties were tuned by side group su...
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In this paper the synthesis of some new chromophores which could be used in polymer/organic LED fabrication are presented. All of them are pyrazoloquinoline (PAQ) derivatives. Their emission proper-ties were tuned by side group substitution. They were characterized by absorption and photoemission spectroscopy. Some were used, dispersed in poly(N-vinylcarbazole) (PVK) matrix, as the emissive layer in LED structures.
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