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Hole-transporting Material (hole-transporting + material)
Selected AbstractsEnhanced-Light-Harvesting Amphiphilic Ruthenium Dye for Efficient Solid-State Dye-Sensitized Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Mingkui Wang Abstract A ruthenium sensitizer (coded C101, NaRu (4,4,-bis(5-hexylthiophen-2-yl)-2,2,-bipyridine) (4-carboxylic acid-4,-caboxylate-2,2,-bipyridine) (NCS)2) containing a hexylthiophene-conjugated bipyridyl group as an ancillary ligand is presented for use in solid-state dye-sensitized solar cells (SSDSCs). The high molar-extinction coefficient of this dye is advantageous compared to the widely used Z907 dye, (NaRu (4-carboxylic acid-4,-carboxylate) (4,4,-dinonyl-2,2,-bipyridine) (NCS)2). In combination with an organic hole-transporting material (spiro-MeOTAD, 2,2,,7,7,-tetrakis-(N,N -di- p -methoxyphenylamine) 9, 9,-spirobifluorene), the C101 sensitizer exhibits an excellent power-conversion efficiency of 4.5% under AM 1.5 solar (100 mW cm,2) irradiation in a SSDSC. From electronic-absorption, transient-photovoltage-decay, and impedance measurements it is inferred that extending the ,-conjugation of spectator ligands induces an enhanced light harvesting and retards the charge recombination, thus favoring the photovoltaic performance of a SSDSC. [source] Modifying the Output Characteristics of an Organic Light-Emitting Device by Refractive-Index Modulation,ADVANCED FUNCTIONAL MATERIALS, Issue 18 2006T. Höfler Abstract In order to modify the output characteristics of organic light-emitting devices (OLEDs), the optical properties of an active layer within the device are patterned without introducing any thickness modulation. For this purpose a new conjugated copolymer, which serves as a hole-transporting material and at the same time can be index patterned using UV techniques, is synthesized. Poly(VC- co -VBT) (VC: N -vinylcarbazole; VBT: 4-vinylbenzyl thiocyanate) is prepared by free-radical copolymerization of VC and VBT. The material contains photoreactive thiocyanate groups that enable altering of the material's refractive index under UV illumination. This copolymer is employed as a patternable hole-transporting layer in multilayer OLEDs. Refractive-index gratings in poly(VC- co -VBT) are inscribed using a holographic setup based upon a Lloyd mirror configuration. The fourth harmonic of a Nd:YAG (YAG: yttrium aluminum garnet) laser (266,nm) serves as the UV source. In this way 1D photonic structures are integrated in an OLED containing AlQ3 (tris(8-hydroxyquinoline) aluminum) as the emitting species. It is assured that only a periodical change of the refractive index (,n,=,0.006 at ,,=,540,nm) is generated in the active material but no surface-relief gratings are generated. The patterned devices show more forward-directed out-coupling behavior than unstructured devices (increase in luminosity by a factor of five for a perpendicular viewing direction). This effect is most likely due to Bragg scattering. For these multilayer structures, optimum outcoupling was observed for grating periods ,,,,390,nm. [source] An Efficient Organic-Dye-Sensitized Solar Cell with in situ Polymerized Poly(3,4-ethylenedioxythiophene) as a Hole-Transporting MaterialADVANCED MATERIALS, Issue 20 2010Xizhe Liu In situ polymerized PEDOT is used as hole-transporting material to fabricate dye-sensitized solar cells (DSSCs) with an average efficiency of 6.1% (under 100,mW,cm,2 AM1.5 illumination) using organic D149 dye as the sensitizer. By comparing with Z907-based devices, the excellent light response of D149-sensitized DSSCs is attributed to the broad light absorption, low photoelectron recombination, and good polymer penetration. [source] Poly(triarylamine): Its synthesis, properties, and blend with polyfluorene for white-light electroluminescenceJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2007Hung-Yi Lin Abstract A new high-molecular-weight poly(triarylamine), poly[di(1-naphthyl)-4-anisylamine] (PDNAA), was successfully synthesized by oxidative coupling polymerization from di(1-naphthyl)-4-anisylamine (DNAA) with FeCl3 as an oxidant. PDNAA was readily soluble in common organic solvents and could be processed into freestanding films with high thermal decomposition and softening temperatures. Cyclic voltammograms of DNAA and PDNAA exhibited reversible oxidative redox couples at the potentials of 0.85 and 0.85 V, respectively, because of the oxidation of the main-chain triarylamine unit. This suggested that PDNAA is a hole-transporting material with an estimated HOMO level of 5.19 eV. The absorption maximum of a PDNAA film appeared at 370 nm, with an estimated band gap of 2.86 eV from the absorption edge. Unusual multiple photoluminescence maxima were observed at 546 nm, and this suggested its potential application in white-light-emission devices. Nearly white-light-emission devices could be obtained with either a bilayer-structure approach {indium tin oxide/poly(ethylenedioxythiophene):poly(styrene sulfonate)/PDNAA/poly[2,7-(9,9-dihexylfluorene)] (PF)/Ca} or a polymer-blend approach (PF/PDNAA = 95:5). The luminance yield and maximum external quantum efficiency of the light-emitting diode with the PF/PDNAA blend as the emissive layer were 1.29 cd/A and 0.71%, respectively, and were significantly higher than those of the homopolymer. This study suggests that the PDNAA is a versatile material for electronic and optoelectronic applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1727,1736, 2007 [source] Dendrimer complexes: Fine control of metal assembly in macromoleculesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2005Kimihisa Yamamoto Abstract New phenylazomethine dendrimers have been developed, with each dendrimer having a unique single structure. From ultraviolet,visible absorption spectra, we determined that stannous chloride added to dendritic polyphenylaz omethine (DPA) was assembled in a stepwise manner from the core shell to the periphery. The selective binding was achieved by the electron density gradient formed in the dendrimer, and it was confirmed by shell-selective imine reduction, transmission electron microscopy, and NMR measurements. The complex formation constants of the respective shells were estimated to be considerably different by a simulation analysis of ultraviolet,visible absorption spectra. The reversible assembly and release of iron into and out of the dendrimer were possible by electrochemical oxidation and reduction, respectively. DPA with a porphyrin at the core was found to function as an effective reduction catalyst of carbon dioxide. DPA with aryl amine at the core was demonstrated to function as a hole-transporting material in electroluminescent devices. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3719,3727, 2005 [source] Synthesis and properties of carbazole-layered polymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2009Yasuhiro Morisaki Abstract New aromatic ring-layered polymers consisting of carbazole as a layered aromatic group and xanthene as a scaffold were designed and synthesized via the Sonogashira,Hagihara coupling reaction. Their optical and electrochemical behaviors were investigated in detail; the results showed that these polymers could be used as hole-transporting materials. Polymers with nitrobenzene moieties at the polymer chain ends quenched the emission from the layered carbazoles to the nitrobenzene termini; thus, the polymers acted as the molecular wire that transferred photoexcited energy and/or electrons to the polymer termini. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4279,4288, 2009 [source] | ||||||||||