Emission Color Tuning with Polymer Molecular Weight for Difluoroboron Dibenzoylmethane-Polylactide (original) (raw)
Macromolecular Research, 2006
A novel, blue light-emitting polymer, poly(phenyl-9,9-dioctyl-9′,9′dihexanenitrile)fluorene (PPFC6N), containing an alkyl and cyano group in the side chain, was synthesized by Suzuki polymerization and characterized. The polymer structure was confirmed by1H-NMR. The number average molecular weight and the weight average molecular weight of the obtained polymer were 9,725 and 9,943 respectively. The resulting polymer was thermally stable with a glass transition temperature (T g ) of 93 °C, and was easily soluble in common organic solvents such as THF, toluene, chlorobenzene and chloroform. The HOMO and LUMO energy levels of the polymer were revealed as 5.8 and 2.88 eV by cyclic voltammetry study, respectively. The ITO/PEDOT:PSS (40 nm)/PPFC6N (80 nm)/LiF (1 nm)/Al (150 nm) device fabricated from the polymer emitted a PL spectrum at 450 nm and showed a real blue emission for pure PPFC6N in the EL spectrum. Whent-butyl PBD was introduced as a hole blocking layer, the device performance was largely improved and the EL spectrum was slightly shifted toward deep blue. The device with PPFC6N containingt-butyl PBD layer showed the maximum luminance of 3,200 cd/m2 at 9.5 V with a turnon voltage of 7 V.
Open Journal of Organic Polymer Materials, 2013
A block copolymer consisting of polyfluorene (PF) and polytriarylamine (PTAA) functionalized with green emitting phenoxazine moiety at the junction point of two blocks was designed and prepared for electroluminescent application. PF homopolymer was synthesized by Suzuki coupling polymerization, and was reacted with brominated phenoxazine. In the presence of the resulting PF functionalized with phenoxazine, C-N coupling polymerization of 4-(4'-bromophenyl)-4''-butyldiphenylamine was carried out to afford a triblock copolymer, PTAA-phenoxazine-PF-phenoxazine-PTAA (PF-Ph-PTAA). Two types of random copolymers were also synthesized with fluorene and phenoxazine (PF2) by Suzuki coupling polymerization for comparison. All the polymers were soluble in common organic solvents and readily formed thin films by a solution processing. Prepared polymers exhibited similar UV absorption and PL emission in chloroform solutions. In a film state, the existence of phenoxazine unit drastically changed PL spectra. Although the content of phenoxazine unit in PF-Ph-PTAA was relatively high (13 mol%), it showed similar PL spectrum to that of PF2(phenoxazine content, 0.2 mol%) indicating that phenoxazine unit is isolated in single polymer chain nevertheless the high content. EL device based on PF-Ph-PTAA showed green-emission, suggesting that emission sites predominantly located in the vicinity of phenoxazine moiety because of its shallow HOMO level.
Color Tuning of Polyfluorene Emission with BODIPY Monomers
Macromolecules, 2009
Three fluorescent conjugated copolymers, comprised of alternating fluorene and BODIPY units in the main chain, have been prepared by palladium-catalyzed Suzuki polymerization of 9,9-dihexylfluorene-2,7-diboronic acid with each of three different 2,6-diiodo-substituted BODIPY monomers. The copolymers were characterized using FT-IR spectroscopy, UV-vis spectroscopy, photoluminescence (PL), and molecular weight studies. Low-band gap BODIPY comonomers are effective in expanding the emission wavelength to the orange region because of significant extension of π-conjugation and have significantly enhanced fluorescent intensity with fluorescent quantum yield of up to 85% in methylene chloride solution. The copolymers show absorption maxima between 547 and 557 nm and emission maxima between 585 and 588 nm in methylene chloride solutions. The copolymers possess high molecular weight, good solubility and readily dissolve in common organic solvents such as THF, CH 2 Cl 2 , CHCl 3 , and toluene. The copolymers display sensitive fluorescent responses to fluoride and cyanide anions through their multivalent interactions while they do not respond to chloride, bromide, and iodide anions.
The Journal of Physical Chemistry A, 2014
The photo-and electroluminescent properties of single-layer two-component blends composed of one blue emitter polymer and one green emitter polymer were studied. The blue emitter, poly[(9,9-dioctylfluorenyl-2,7diyl)-alt-co-(9,9-di-{5′-pentanyl}-fluorenyl-2,7-diyl)] (PFOFPen), was used as the matrix, and the green emitter, poly[(9,9-dihexylfluorenyl-2,7-diyl)-alt-co-(bithiophene)] (F6T2), was used as the guest. The F6T2 content in the blends varied from 0.0075 wt % to 2.4 wt %. Remarkable differences were observed between the electroluminescent (EL) and photoluminescent (PL) spectra of these blends, which indicated that the mechanism for excited-state generation in the former process had a higher efficiency in the aggregated phase than in the nonaggregated phase. Blending these two polymers gradually tuned the emission color from blue (PFOFPen and blends with <0.75 wt % F6T2) to green (F6T2 and blends with >0.75 wt % F6T2). The photophysical processes involved in both EL and PL emission are also discussed.
Materials
Using palladium-catalyzed Suzuki polycondensation, we synthesized new light-emitting fluorene copolymers containing the dicyano derivatives of stilbene and phenanthrene and characterized them by gel permeation chromatography, UV-vis absorption spectroscopy, spectrofluorimetry, and cyclic voltammetry. The photoluminescence spectra of the synthesized polymers show significant energy transfer from the fluorene segments to the dicyanostilbene and 9,10-dicyanophenanthrene units, which is in agreement with the data of theoretical calculations. OLEDs based on these polymers were fabricated with an ITO/PEDOT-PSS (35 nm)/p-TPD (30 nm)/PVK (5 nm)/light emitting layer (70–75 nm)/PF-PO (20 nm)/LiF (1 nm)/Al (80 nm) configuration. Examination of their electroluminescence revealed that copolymers of fluorene with dicyanostilbene show yellow-green luminescence, while polymers with 9,10-dicyanophenanthrene have a greenish-blue emission. The 9,10-dicyanophenanthrene units have a more rigid structure...
Synthesis and Optical Properties of Light-Emitting Polyfluorene Derivatives
Molecular Crystals and Liquid Crystals, 2011
The emitting-polymers, Polyfluorene (PF) and Poly(fluorene-benzothiadiazole-quinoline) [PF-BT-QL], have been synthesized by the Suzuki coupling reactions. The properties of polymers were characterized using UV-Vis spectroscopy, GPC, DSC, TGA, Photoluminescence (PL), Fluoresence (FL), Electroluminescence (EL) spectroscopy. The synthetic polymers were soluble in common organic solvents and easily spin-coated onto the indium-tin oxide (ITO)-coated glass substrates. Light-emitting devices (LEDs) with ITO/PEDOT:PSS/polymer/LiF/Al configuration were fabricated, and the devices using copolymers showed red shift EL spectra relative to that of PF. The turns on voltages of copolymers were lower than that of PF.
Journal of Polymer Science Part A: Polymer Chemistry, 2006
Poly(9,9-dihexylfluorene-2,7-vinylene-alt-dibenzothiophene-2,8-vinylene) (PS) and poly (9,9-dihexylfluorene-2,7-vinylene-alt-dibenzothiophene-5,5-dioxide-2,8vinylene) (PSO) as well as corresponding model compounds were synthesized by Heck coupling. Both the polymers and model compounds were readily soluble in common organic solvents such as tetrahydrofuran, dichloromethane, chloroform, and toluene. The polymers showed a decomposition temperature at $430 8C and a char yield of about 65% at 800 8C in N 2 . The glass-transition temperatures of the polymers were almost identical (75-77 8C) and higher than those of the model compounds (26-45 8C). All samples absorbed around 390 nm, and their optical band gaps were 2.69-2.85 eV. They behaved as blue-greenish light emitting materials in both solutions and thin films, with photoluminescence emission maxima at 450-483 nm and photoluminescence quantum yields of 0.52-0.72 in solution. Organic light-emitting diodes with an indium tin oxide/ poly(ethylene dioxythiophene):poly(styrene sulfonic acid)/polymer/Mg:Ag/Ag configuration with polymers PS and PSO as emitting layers showed green electroluminescence with maxima at 530 and 540 nm, respectively. V V C 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6790-6800, 2006