Synthesis and luminescence properties of new blue‐light‐emitting polyconjugated poly{1,1′‐biphenyl‐4,4′‐diyl‐[1‐(4‐t‐butylphenyl)]vinylene} polymers and copolymers

Three new soluble polyconjugated polymers, all of which emitted blue light in photoluminescence and electroluminescence, were synthesized, and their luminescence properties were studied. The polymers were poly{1,1′‐biphenyl‐4,4′‐diyl‐[1‐(4‐t‐butylphenyl)]vinylene}, poly((9,9‐dioctylfluorene‐2,7‐diyl)‐alt‐{1,4‐phenylene‐[1‐(4‐t‐butylphenyl)vinylene‐1,4‐phenylene]}) [P(DOF‐PVP)], and poly([N‐(2‐ethyl) hexylcarbazole‐3,6‐diyl]‐alt‐{1,4‐phenylene‐[1‐(4‐t‐butylphenyl)]vinylene‐1,4‐phenylene}). The last two polymers had alternating sequences of the two structural units. Among the three polymers, P(DOF‐PVP) performed best in the light‐emitting diode devices of indium–tin oxide/poly(ethylenedioxythiophene) doped with poly(styrene sulfonate) (30 nm)/polymer (150 nm)/Li:Al (100 nm). This might have been correlated with the balance in and magnitude of the mobility of the charge carriers, that is, positive holes and electrons, and also the electronic structure, that is, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels, of the polymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 307–317, 2006     

Blue light‐emitting poly(p‐phenylenevinylene) derivative with oxadiazole and carbazole pendant groups

A blue light‐emitting statistical poly(p‐phenylenevinylene) (PPV) copolymer with hole‐transporting carbazole and electron‐transporting oxadiazole pendant groups attached to the kinked m‐terphenyl unit was prepared by Heck coupling between 1,4‐divinylbenzene and dibromides. The latter were synthesized through pyrylium salts. The polymer had optical band gap of 2.89 eV and emission maximum at 446 nm in THF solution and 434 nm in thin film. It showed a pure blue emission with no aggregates or excimers formed even in solid state because of the long and bulky pendant groups. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3842–3849, 2006     

Substituent effect on the optoelectronic properties of poly(p‐phenylenevinylene) based conjugated‐nonconjugated copolymers

Two classes of light emitting Poly(p‐phenylenevinylene) (PPV) based conjugated‐nonconjugated copolymers (CNCPs) have been synthesized. The conjugated chromophores containing 2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene (MEHPV) and 2,5‐dimethyl‐1,4‐phenylenevinylene (DMPV) moieties are rigid segments and nonconjugated portion containing hexyl units are flexible in nature. All copolymers were synthesized by well‐known Wittig reaction between the appropriate bisphosphonium salts and the dialdehyde monomers. The resulting polymers were found to be readily soluble in common organic solvents like chloroform, THF and chlorobenzene. The effect of chromophore substituents on the optical and redox properties of the copolymers has been investigated. Color tuning was carried out by varying the molar percentage of the comonomers. The UV‐Vis absorption and PL emission of the copolymers were in the range 314–395 nm and 494–536 nm respectively. All the polymers show good thermal stability. Polymer light‐emitting diodes (PLEDs) were fabricated in ITO/PEDOT:PSS/emitting polymer/cathode configurations of selected polymers using double‐layer, LiF/Al cathode structure. The emission maxima of the polymers were around 499–536 nm, which is a blue‐green part of the color spectrum. The threshold voltages of the EL polymers were in the range of 5.4–6.2 V. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis,electroluminescence, and photovoltaic cells of new vinylene‐copolymers with 4‐(anthracene‐10‐yl)‐2,6‐diphenylpyridine segments

Three new soluble vinylene‐copolymers F , C, and P that contain 4‐(anthracene‐10‐yl)‐2,6‐diphenylpyridine as common segment and fluorene, carbazole, or phenylene, respectively, as alternating segment were prepared by Heck coupling. The glass transition temperature was high for F and C (110 and 117°C), whereas was lower than 25°C for P . The polymers were stable up to ～ 300°C. They emitted blue–green light with maximum located at wavelength of 456–550 nm, which was of the order F < C < P . The photoluminescence quantum efficiency in THF solution was ～ 30% for F and P and only 5% for C . All three copolymers were used as active layers for polymer light emitting diodes (PLEDs) and organic photovoltaic cells. The double PLEDs with configuration of indium‐tin oxide (ITO)/poly(ethylenedioxythiophene (PEDOT) : poly(styrenesulfonate)(PSS)/Copolymer F , C , or P /TPBI(1,3,5‐tris(2‐N‐phenylbenzimidazolyl)benzene)/Ca/Al were fabricated. Copolymer P emitted green light with maximum brightness of 28 cd/m² and a current yield of 0.85 cd/A. Organic photovoltaics with the configuration of ITO/PEDOT : PSS/Copolymer and [6,6]‐phenyl‐C61‐butyric acid methyl ester blend (1 : 1) /Ca/Al were also fabricated. Copolymer P showed the highest power conversion efficiency of 0.034%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Luminescent supramolecular polymers: Cd2+‐directed polymerization and properties

A family of supramolecular polymers was prepared via Cd²⁺‐directed self‐assembly polymerization of bis(2,2′:6′,2″‐terpyridine)‐based ligand monomers, using oligofluorenes and triphenylamine as bridges under mild conditions. The polymers were fully characterized using thermogravimetric analysis, inherent viscosity, electrochemical measurements, UV‐visible spectroscopy, photoluminescence (PL) and electroluminescence (EL). Polymers with oligofluorenes as spacers exhibited blue emission (434–442 nm) in dimethyl acetamide (DMAc) solution, while polymers with triphenylamine as spacer presented an emission peak at 494 nm in DMAc solution. Complexation polymerization of bis(2,2′:6′,2″‐terpyridine)‐based ligand monomers with cadmium(II) improved fluorescence quantum yields dramatically, and the film PL quantum yields of these polymers were about 0.38–0.54. Single‐layer light‐emitting diodes were fabricated with the configuration indium tin oxide (ITO)/polymer/Ca/Al; the EL showed green emission and the onset voltages of the devices were 8–11 V. Copyright © 2006 Society of Chemical Industry     

Blue‐light‐emitting poly(arylene ethynylenes) containing alternating sequences of biphenylene or fluorenediyl and p‐phenylene moieties linked through triple bonds

Two new poly(arylene ethynylenes) were synthesized by the reaction of 1,4‐diethynyl‐2.5‐dioctylbenzene either with 4,4′‐diiodo‐3,3′‐dimethyl‐1,1′‐biphenyl or 2,7‐diiodo‐9,9‐dioctylfluorene via the Sonogashira reaction, and their photoluminescence (PL) and electroluminescence (EL) properties were studied. The new poly(arylene ethynylenes) were poly[(3,3′‐dimethyl‐1,1′‐biphenyl‐4,4′‐diyl)‐1,2‐ethynediyl‐(2,5‐dioctyl‐1,4‐phenylene)‐1,2‐ethynediyl] (PPEBE) and poly[(9,9‐dioctylfluorene‐2,7‐diyl)‐1,2‐ethynediyl‐(2,5‐dioctyl‐1,4‐phenylene)‐1,2‐ethynediyl] (PPEFE), both of which were blue‐light emitters. PPEBE not only emitted better blue light than PPEFE, but it also performed better in EL than the latter when the light‐emitting diode devices were constructed with the configuration indium–tin oxide/poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonic acid) (50 nm)/polymer (80 nm)/Ca:Al. The device constructed with PPEBE exhibited an external quantum efficiency of 0.29 cd/A and a maximum brightness of about 560 cd/m², with its EL spectrum showing emitting light maxima at λ = 445 and 472 nm. The device with PPEFE exhibited an efficiency of 0.10 cd/A and a maximum brightness of about 270 cd/m², with its EL spectrum showing an emitting light maximum at λ = 473 nm. Hole mobility (μ_h) and electron mobility (μ_e) of the polymers were determined by the time‐of‐flight method. Both polymers showed faster μ_h values. PPEBE revealed a μ_h of 2.0 × 10^?4 cm²/V·s at an electric field of 1.9 × 10⁵ V/cm and a μ_e of 7.0 × 10^?5 cm²/V·s at an electric field of 1.9 × 10⁵ V/cm. In contrast, the mobilities of the both carriers were slower for PPEFE, and its μ_h (8.0 × 10^?6 cm²/V·s at an electric field of 1.7 × 10⁶ V/cm) was 120 times its μ_e (6.5 × 10^?8 cm²/V·s at an electric field of 8.6 × 10⁵ V/cm). The much better balance in the carriers' mobilities appeared to be the major reason for the better device performance of PPEBE than PPEFE. Their highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels were also a little different from each other. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 299–306, 2006     

Synthesis,characterization, and optoelectronic properties of two new polyfluorenes/poly(p‐phenylenevinylene)s copolymers

Two novel copolymers of polyfluorenes/poly(p‐phenylenevinylene)s copolymers with p‐tert‐butyl‐phenylenemethylene groups in the C‐9 position of alternating fluorene unit, poly[1,4‐(2,5‐dibutyloxyl)‐phenyleneviny lene‐alt‐9‐(p‐tert‐butyl‐phenylenemethylene)fluorene] and poly[1,4‐(2,5‐dioctyloxyl)‐phenylenevinylene‐alt‐9‐(p‐tert‐butyl‐phenylenemethylene)fluorine], have been synthesized via the Heck polycondensation reaction. The synthesized polymers were characterized by FTIR, NMR, DSC, TGA, UV–vis, and PL spectra. The polymers showed high glass transition temperatures and good thermal stability. A polymer light‐emitting diode with the configuration ITO/PEDOT:PSS/P2/Ca/Al has been fabricated. The device emitted a yellow light with a peak wavelength of 578 nm similar to the PL spectra of the copolymer film. A maximal luminance of 534 cd/m² was obtained at a driving voltage of 24.5 V. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3955–3962, 2006     

Synthesis and electroluminescent properties of a novel copolymer with short alternating conjugated and non‐conjugated blocks

A new electroluminescent copolymer [poly(1,5‐di(3,5‐dimethyloxystyrylene)naphthalene‐block‐tri(ethylene oxide)) (DSN–TEO)], containing alternating rigid, conjugated light‐emitting units and flexible tri(ethylene oxide) ionic conductive units, was synthesized via the Wittig reaction. The polymer has fairly good solubility in chloroform, tetrahydrofuran, toluene, etc, and excellent film‐forming ability. The decomposition temperature and the glass transition temperature were 409 °C and 42.2 °C, respectively. A light‐emitting diode (LED) device with configuration ITO/PEDOT–PSS/DSN–TEO/Ca(Al) and light‐emitting electrochemical cell (LEC) device with ITO/DSN–TEO + PEO (LiTf)/Al were prepared, and the photoluminescence and electroluminescence (EL) properties were investigated. Efficient blue‐green light emission (EL maximum emissive wavelength at 508 nm) was found with onset voltage at 6 V. The maximum light efficiency was 0.107 cd A^?1 at 20 V for LED, and the onset voltage 2.5 V and the maximum light efficiency was 4.2 cd A^?1 at 2.8 V for LEC, respectively. The response time of the LEC was less than 5 s. The EL efficiency of LEC device was improved by 44 as compared with the relative LED device. © 2003 Society of Chemical Industry     

Studies on the synthesis and optical properties of novel blue light‐emitting polymers containing phosphorus and oxadiazole structures

Novel phosphorus‐containing polymers with high‐electron‐affinity oxadiazole were synthesized and characterized by thermal analysis and spectroscopy (infrared, ultraviolet‐visible, photoluminescence, cyclic voltammetry) measurements. These new polymers can be used as blue electroluminescent materials and as electron‐transport layers in polymer light‐emitting diodes. In this study, aromatic polyethers containing electron‐transporting chromophores and emission chromophores were synthesized from 2,5‐bis‐(4‐fluoroaryl)‐1,3,4‐oxadiazole and 2‐(6‐oxido‐6H‐dibenz<c,e><1,2> oxaphosphorin‐6‐yl)‐1,4‐naphthalenediol (DOPO‐NBQ). The effects of reaction temperature and time on the formation of polyethers were investigated to obtain optimum conditions for polyether manufacturing. All the resulting polymers were thermally stable at <460 °C. The absorption peaks of these polymers were at 350–365 nm, whereas the photoluminescent peaks were at 460–481 nm. But, the intensity of polymer absorption decreased and a blue shift was observed in the photoluminescent spectra as the temperature increased. In addition, these polymers containing the electron‐transporting oxadiazole indeed showed extra reduction potentials in cyclic voltammetry measurements. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2367–2376, 2002     

Synthesis and fluorescence of polymeric triphenylamine obtained by oxidative‐coupling polymerization

We prepared triphenylamine (TPA)‐containing polymers by a direct oxidative‐coupling method, which showed high thermostability, good solubility, high quantum efficiency, and blue light emission. The polymers are characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, ultraviolet–visible spectroscopy, thermogravimetric analysis, elemental analysis, and fluorescence spectra. The homopolymeric TPA (PTPA) was fairly soluble in CCl₄ and toluene, with a quantum yield of 0.38 relative to Rhodamine B in toluene solution, and showed blue light emission in solid‐state film. The TPA–stilbene copolymers were more soluble than the PTPA and showed violet to green light emission in solid‐state film, depending on the TPA moiety contents, from which a pure blue light emission could be obtained. The emitting quantum efficiency of the copolymers measured in toluene solution was from 0.57 to 0.78 relative to Rhodamine B. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2718–2724, 2002     

Eu2+‐Doped Yellow‐Emitting CsBaB3O6 Glass‐Ceramic Prepared by Melt Quenching and Re‐Crystallization Method

Eu³⁺‐doped cesium barium borate glass with the composition of Cs₂O·2BaO·3B₂O₃ was prepared by the conventional melt quenching method. The glass‐ceramic sample was obtained from the re‐crystallization of the as‐made glass to change the amorphous glass into a crystalline host. This reduces the Eu³⁺ in glass to Eu²⁺ ions resulting in a yellow‐emitting phosphor of Eu²⁺‐activated CsBaB₃O₆. The samples were investigated by the XRD patterns and SEM micrograph, the optical absorption, the photoluminescence spectra, and decay curves. The as‐made glass has only Eu³⁺ centers. Under the excitation of blue or near‐UV light, Eu²⁺‐doped CsBaB₃O₆ presents yellow‐emitting color from the allowed inter‐configurational 4f–5d transition in the Eu²⁺ ions. The maximum absolute luminescence quantum efficiencies of Eu²⁺‐doped CsBaB₃O₆ phosphor was measured to be 47% excited at 430 nm light at 300 K. By taking into account the efficient excitation in blue wavelength region, this new phosphor could be a potential yellow‐emitting phosphor for an application in white light‐emitting diodes fabricated with blue chips.     

Magnetic properties of polystyrene‐b‐poly(2‐hydroxylethyl methacrylate)/metal hybrids

Hybrids, which were composed of the amphiphilic diblock copolymer polystyrene‐b‐poly(2‐hydroxylethyl methacrylate) (PSt‐b‐PHEMA) and nickel, cobalt, or a nickel–cobalt alloy, were characterized with infrared absorption spectroscopy and ultraviolet–visible (UV–vis) absorption spectroscopy. UV–vis spectroscopy analysis showed that a redshift happened after the PSt‐b‐PHEMA/metal‐ion complexes were reduced by KBH₄. The PSt‐b‐PHEMA/nickel–cobalt alloy hybrids had the biggest redshift [difference of the UV‐vis absorption wavelength between (PSt‐b‐PHEMA)/metal ion complex and (PSt‐b‐PHEMA)/metal hybrids (Δλ_m = 19.9 nm)]. In comparison with the PSt‐b‐PHEMA/nickel hybrids (Δλ_m = 3.5 nm) and PSt‐b‐PHEMA/cobalt hybrids (Δλ_m = 9.0 nm). The magnetic properties of PSt‐b‐PHEMA/metal were studied with vibrating sample magnetometry. The results of magnetic hysteresis loop studies showed that the obtained PSt‐b‐PHEMA/metal hybrids could be categorized as ferromagnetic materials. The results showed that the magnetic susceptibility decreased with increasing temperature in the range of 150–400 K and increased with increasing temperature above 400 K. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Synthesis and studies of blue light emitting polymers containing triphenylamine‐substituted fluorene and diphenylanthracene moiety

Photoluminescent (PL) polymers containing triphenylamine‐substituted fluorene and diphenylanthracene (DPA) units were synthesized by aromatic nucleophilic substitution reaction. The light emitting polymers (LEPs) contains hole‐transporting triphenylamine (TPA) groups at the C‐9 position of fluorene and DPA‐emitting segments in the main chain. The obtained polymers were soluble in various organic solvents and thermally stable. The synthesized polymers were successfully characterized by elemental analyses, FTIR and, ¹H NMR spectroscopy. The electrochemical measurements and optical properties of the polymers were also studied. The obtained polymers showed significant blue emission. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Novel redox‐active polycarbazole‐functionalized polycatechol network films produced by controlled electropolymerization

A novel precursor, 1,2‐bis[6‐(9H‐carbazol‐9‐yl)hexyloxy] benzene (BCHB), was successfully synthesized. Its polycarbazole‐functionalized polycatechol network films, poly{1,2‐bis[6‐(9H‐carbazol‐9‐yl)hexyloxy] benzene} (PBCHB), with good redox activity were formed by the direct anodic oxidation of BCHB in CH₂Cl₂ and boron trifluoride diethyl etherate binary solvent solution. Ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, ¹H‐NMR, and matrix‐assisted laser desorption ionization–time of flight mass spectrometry were used to characterize the polymers. The results indicate that the network polymers could be synthesized electrochemically with different polymerized units by controlled electropolymerization. The PBCHB films prepared at low potential were oligomers with short conjugation lengths and were soluble in common organic solvents, whereas the polymers with long conjugation lengths and hyperbranched network structures obtained at high potential were insoluble. The electrosynthesized polymers exhibited blue emission maxima around 450 nm and were much more redshifted than their monomer. The emissions were also brighter; this indicated the polymers are potential good blue‐light emitters. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Enhanced performance of polymer light‐emitting device via optimization of processing conditions and device configuration

The improved performance of polyalkylfluorene light‐emitting device has been achieved through the optimization of processing conditions and device configuration. The current density, brightness, power efficiency, and operation lifetime of polymer light‐emitting device (PLED) were strongly dependent on the surface treatment of anode, the film thickness of light‐emitting polymer (LEP), and the cathode configuration. The anode surface treated with O₂ plasma exhibited a higher current density and brightness than the CF₄ plasma treated device. However, better operation stability was obtained for the CF₄ plasma treated device than for the O₂ plasma treated device. The maximum of brightness and power efficiency has been achieved for the PLED with an LEP thickness of 80 nm. The PLED with LiF/Ca/Al cathode possesses a better power efficiency and operation stability than does the Ca/Al or LiF/Al based PLED. The influences of device fabrication conditions and device configuration on the performance of a polyalkylfluorene‐based PLED are discussed in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 133–141, 2006     

Continuously tunable broadband emission of Mn2+‐doped low‐melting point Sn–F–P–O glasses for warm white light‐emitting diodes

Tin fluorophosphate (TFP) glass, which can be used to manufacture a phosphor‐in‐glass (PiG) for achieving high‐power white light‐emitting diodes (w‐LEDs), has attracted a great deal of attention because of its low‐melting point. Mn²⁺‐doped ultralow glass transition temperature (~122°C) Sn–F–P–O glasses were prepared to achieve broadband visible light emission from 390 to 720 nm. By controlling the concentration of MnO, the emission color of the TFP glass can be adjusted from blue/cool white to warm white/red. In particular, 0.2 mol% MnO‐doped TFP glass, which yields bright and warm white light and has ultralow glass transition temperature and thermal stability, has a promising application prospect in the field of high‐power w‐LEDs.     

Enhancing the electroluminescence properties of novel blue light emitting polymer and MEH‐PPV based white light emitting polymer devices by processing condition optimization

A series of triarylaminooxadiazole‐containing tetraphenylsilane light emitting polymer (PTOA) and poly(2‐methoxy, 5‐(2′‐ethyl‐hexyloxy)‐p‐phenylene‐vinylene) (MEH‐PPV) based white light emitting polymer devices (PLEDs) were fabricated to study blue and orange–red emitter composition and light emitting layer processing effects on white emission electroluminescence properties. Color purity, current turn‐on voltage, brightness, and current efficiency were strongly determined by MEH‐PPV content and the thin film processing condition. The intensity of PTOA blue emission was equal to that of MEH‐PPV orange–red emission when the device was fabricated by a polymer composite film containing 10 wt % of MEH‐PPV. Color purity [Commission Internationale de L'Eclairage (CIE_x,y) coordinates (0.26,0.33)] was nearly white emission under applied 8 V. The brightness and current efficiency of PTOA‐MEH‐PPV composite film based devices increased as MEH‐PPV content increased. Furthermore, white emission blue shifted with increasing spin‐rate of thin film coating and applied voltage. Low turn‐on voltage, high current density, and high brightness were obtained for the device fabricating with light emitting layer coating with high spin‐rate. Moreover, low current efficiency was obtained for the PLED with a thinner light‐emitting layer. A white emission CIE (0.28,0.34) was obtained for PTOA‐MEH‐PPV based white PLED. White PLED brightness and efficiency can be as high as 700 cd/m² and 0.78 cd/A, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Indium tin oxide nanoparticles as anode for light‐emitting diodes

Thin films of indium tin oxide (ITO) nanoparticles have been investigated as anode materials for polymer light‐emitting diodes. A luminance efficiency (0.13 cd/A), higher than that (0.09 cd/A) obtained in a control devices fabricated on conventional commercial ITO anodes were found. The thin films were made by spin coating of a suspension followed by annealing. The ITO nanoparticle films have a stable sheet resistance of 200 Ω/sq, and an optical transmittance greater than 86% over the range of 400–1000 nm. Their textural property is also reported. These results demonstrate that ITO nanoparticle can form a high efficient reproducible anode material. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3125–3129, 2006     

Synthesis and characterization of organosoluble polyfluorinated polyimides derived from 3,3′,5,5′‐tetrafluoro‐4,4′‐diaminodiphenylmethane and various aromatic dianhydrides

A polyfluorinated aromatic diamine, 3,3′, 5,5′‐tetrafluoro‐4,4′‐diaminodiphenylmethane (TFDAM), was synthesized and characterized. A series of polyimides, PI‐1–PI‐4, were prepared by reacting the diamine with four aromatic dianhydrides via a one‐step high‐temperature polycondensation procedure. The obtained polyimide resin had moderate inherent viscosity (0.56–0.68 dL/g) and excellent solubility in common organic solvents. The polyimide films exhibited good thermal stability, with an initial thermal decomposition temperature of 555°C–621°C, a 10% weight loss temperature of 560°C–636°C, and a glass‐transition temperature of 280°C–326°C. Flexible and tough polyimide films showed good tensile properties, with tensile strength of 121–138 MPa, elongation at break of 9%–12%, and tensile modulus of 2.2–2.9 GPa. The polyimide films were good dielectric materials, and surface and volume resistance were on the order of a magnitude of 10¹⁴ and 10¹⁵ Ω cm, respectively. The dielectric constant of the films was below 3.0 at 1 MHz. The polyfluorinated films showed good transparency in the visible‐light region, with a cutoff wavelength as low as 302 nm and transmittance higher than 70% at 450 nm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1442–1449, 2007     

Synthesis and properties of partially conjugated hyperbranched light‐emitting polymers

Via A₂ + B₄ and A₂ + B₃ [where A₂ is 1,4‐distyrylol‐2,5‐butoxybenzene, B₃ is 1,1,1‐tris‐(p‐tosyloxymethyl)‐propane, and B₄ is pentaerythritol tetra(methyl benzene sulfonate)] approaches, we synthesized two kinds of partially conjugated hyperbranched polymers, hyperbranched polymer with 3 arms (HP1) and hyperbranched polymer with 4 arms (HP2), which had rigid conjugated segments [oligo‐poly(phenylene vinylene)] and flexible, nonconjugated spacers arranged alternately through ether bonds in the skeleton. The conjugated segments were modified by pendant butoxy groups, which imparted the resulting polymers with excellent solubility in common organic solvents and excellent film‐forming abilities. Fourier transform infrared and nuclear magnetic resonance spectroscopy were used to identify the structure of the monomers and polymers. Thermal property investigations showed that two polymers both had good thermal stability with their decomposition temperatures in the range 396–405°C and high glass‐transition temperatures, which are of benefit to the fabrication of high‐performance light‐emitting devices. The photophysical properties were studied, and the relative photoluminescence quantum efficiencies of HP1 and HP2 in dilute chloroform solution amounted to 56.8 and 49.3%, respectively. A brief light‐emitting diode device with a configuration of indium tin oxide/HP1/Ca/Al was fabricated, and its electroluminescence performance was studied. The brightness of the device reached an optimistic maximum of 190 cd/m² at 8.2 V. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010