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Poly(phenylene ethynylene)- alt-poly(phenylene vinylene)s (PPE-PPVs) with various thiophene units (thiophene, bithiophene, and 3,4-ethylenedioxythiophene) at the X position, with the general backbone design (PhCC XCCPhCHCHPhCHCH), bearing identical solubilizing side chains at the phenylene rings of the polymers, are synthesized to study the effect of this structural alteration on the properties such as the photophysics, the electrochemical properties, the charge-carrier mobility, and the morphology of the materials and its impact on their photovoltaic performance. The polymers are obtained in good yields with reasonable molecular weights and show solubility in ordinary organic solvents required for solution-processing applications. The polymer with a basic thiophene ring at the X positions shows the highest open-circuit voltage ( VOC of 930 mV) and the polymer with a bithiophene unit at the X position shows the highest short-circuit current density and charge-carrier mobility, whereas the polymer with 3,4-ethylenedioxythiophene shows the lowest photovoltaic performance. [ABSTRACT FROM AUTHOR]

ABSTRACT An anthracene-containing poly(arylene-ethynylene)- alt-poly(arylene-vinylene) (PAE-PAV) of general constitutional unit (PhCCAnthrCCPhCHCHAnthrCHCH) n bearing two 2-ethylhexyloxy solubilizing side chains on each phenylene (Ph) unit has been synthesized and characterized. The basic electrochemical characterization was done, showing the existence of two non-reversible oxidation and one reversible reduction peaks. The optical properties, the real and imaginary part of the dielectric function, were probed using spectroscopic ellipsometry (SE). The vibrational structure of the undoped/doped polymer was investigated using Fourier transformed infrared spectroscopy. A strong change in the polaronic absorption was observed during the doping, which after modeling revealed the existence of two separated transitions. The optical changes upon doping were additionally recorded using the SE technique. Similar to the results from FT-IR spectroscopy, two new in-the-gap absorptions were found. Moreover, the electrical conductivity as well as the mobility of positive carriers were measured. In the undoped state, the conductivity of the polymer was found to be below the detection limit (<μS cm−1), after doping the conductivity increased to 0.69 S cm−1. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 338-346 [ABSTRACT FROM AUTHOR]

In the current work, the exact analytical expression of the current–voltage characteristics, which are given in terms of the L a m b e r t W function, is used to extract the physical parameters of organic and inorganic Schottky barrier diodes (SBDs). The extraction is achieved by a variety of methods using the experimental I–V characteristics. The organic SBD is based on a Poly (3-hexylthiophene-2,5-diyle) conjugated polymer (P3HT) with Al contact, measured at 300 K. Regarding the inorganic SBDs, one is based on Iridium–Silicon Carbide (Ir–SiC), measured at 300 K, and the second diode is based on Gold–Gallium Arsenide (Au–GaAs), measured at 200 K. The numerical characteristics based on the physical parameters extracted by the presented methods are in good agreement with the experimental data. The determination coefficient of the modeling methods for the three SBDs is higher than 99.99%. [ABSTRACT FROM AUTHOR]

The combination of Heck–Cassar–Sonogashira–Hagihara reaction, column chromatography, leading to the synthesis of luminophoric dialdehydes 5, and the subsequent Horner–Wadsworth–Emmons polycondensation reactions of 5 and the bisphosphonates 3 enables the synthesis of a new type of defect-free π-conjugated polymers with well defined general structure –(Ar–C≡C–Ar–C≡C–Ar–CH=CH–Ar–CH=CH–)[sub n], 7. The chemical structure was confirmed by NMR, infrared and UV/Vis spectroscopy. High molecular weight (M[sub w] up to 500 000 g/mol), thermostable, soluble and transparent film forming materials were obtained. The new compounds show thermotropic and lyotropic mesomorphic behavior on polarized optical microscopy. The incorporation of triple bonds into the PPV backbone increases the oxidation and the reduction potentials, thus making these polymers potentially good electron transporting materials if used in light-emissive-diodes devices. The polymers are photoconductive and show very good photoluminescent properties in solution as well as in solid state. Identical absorption (λ[sub max,abs] = 445 nm) and emission (λ[sub max,em] = 490 nm) behaviors were observed for all polymers in solution (CHCl[sub 3]), resulting to a fluorescence quantum yield of 70%, but the photophysical behavior in solid state was side groups-dependent. The orange-coloured polymer 7ac (R[sup 2] = (CH[sub 2])[sub 7]CH[sub 3]; λ[sub max,abs] = 465 nm; λ[sub max,em] = 602 nm) is characterized with a very large Stokes shift (137 nm) and lower fluorescence quantum yield (19%), whereas the yellow-coloured polymers 7aa, 7bb and 7ab, consisting of side groups equal or longer than O(CH[sub 2])[sub 11]CH[sub 3](λ[sub max,abs] = 480 nm, λ[sub max,em] = 508 nm) were characterized with smaller Stokes shift (around 30 nm) and comparatively higher fluorescence quantum yields (34 to 44%); as a result of hindered interchain π -π interactions, and consequently limited formation of excimer complexes, which are regarded as an important deactivation channel of the excitons. [ABSTRACT FROM AUTHOR]

Abstract--An improved and simplified synthetic method for 4-bromo-2,2'-bipyridine (5) has opened a way to the synthesis of the model compounds 8a, b of polymer 9. 8a, b confirmed the effective conjugation segment of polymer 9 to consist of an alternation of three aryl and two ethynyl units (Ar--C Is equivalent to C--Ar--C Is equivalent to C--Ar) due to the zig-zag structure of the polymer. It was found to be the smallest conjugated unit necessary to obtain excellent fluorescence. [ABSTRACT FROM AUTHOR]

Novel 2,2′-bipyridine-based conjugated polymers of formula 2 have been synthesized by Pd-catalyzed cross-coupling reactions between 4,4′-dibromo-2,2′-bipyridine (3) and substituted phenyldiacetylenes (4). The zig-zag arrangement of the 2,2′-bipyridine units implies a helical conformation of 2. The solubility of 2 requires at least a dodecyl side-chain. 2 is thermostable up to 400°C. The polymers have a high fluorescence quantum yield in solution (60%). [ABSTRACT FROM AUTHOR]