Novel green light-emitting polyfluorenes containing dibenzothiophene-S,S-dioxide-arylamine derivatives

Green light-emitting polyfluorenes were synthesized by Suzuki polycondensation via introducing dibenzothiophene-S,S-dioxide-(di-)tri-phenylamine (G₁ and G₂) moieties and dibenzothiophene-S,S-dioxide (SO) unit into the polyfluorene backbone, respectively. PF–SO–G copolymers show a high thermal stability and a moderate photoluminescence quantum yield in the range of 20–40%. The lowest unoccupied molecular orbital (LUMO) levels reduce with increasing the content of SO unit in the polymers. The efficient energy transfer from fluorene segment to G₁ or G₂ unit occurred in the PL process, and the EL emission peaked at about 510 nm was exclusively from G₁ or G₂ unit. Incorporating SO unit into the polymer backbone makes the device performances improved. The maximal luminous efficiency of 9.0 cd A^?1 with the CIE coordinates of (0.27, 0.56) was obtained for PF–SO15-G₂5 based on a single-layered device of ITO/PEDOT:PSS/polymer/CsF/Al. And the polymers (PF–SO15-G5)s exhibited a dramatic LE stability at high current densities, even though at the current density of 200 mA cm^?2, the luminous efficiencies only dropped 10%. SO unit lowers the LUMO level, balances the injection and transportation of both electron and hole in the polymers, and therefore improves the device performances. The hole- and electron-only devices show that the hole and electron flux are well balanced, which demonstrates that (PF-SO15-G5)s are bipolar polymers with a balanced charge carrier transport.     

Novel fluorine containing polyfluorenes with efficient blue electroluminescence

The synthesis, structural characterization, photo and electroluminescence, thermal and electrochemical properties of a new fluorinated fluorene-containing copolymer are described. The copolymer is formed by alternating mers of [2,3,5,6 tetrafluoro-1,4 phenylene] and [9,9′-dihexyl-2,7 fluorene] and emits blue light with low turn on voltages. The EL performance of the fluorinated copolymer was superior to those of the non-fluorinated analog copolymer and of the corresponding poly(9,9′dihexyl-2,7 polyfluorene) homopolymer.     

Novel yellow phosphorescent iridium complexes containing a carbazole-oxadiazole unit used in polymeric light-emitting diodes

Yellow iridium complexes Ir(PPOHC)₃ and (PPOHC)₂Ir(acac) (PPOHC: 3-(5-(4-(pyridin-2-yl)phenyl)-1,3,4-oxadiazol-2-yl)-9-hexyl-9H-carbazole) were synthesized and characterized. The Ir(PPOHC)₃ complex has good thermal stability with 5% weight-reduction occurring at 370 °C and a glass-transition temperature of 201 °C. A polymeric light-emitting diode using the Ir(PPOHC)₃ complex as a phosphorescent dopant showed a luminance efficiency of 16.4 cd/A and the maximum external quantum efficiency of 6.6% with CIE coordinates of (0.50, 0.49). A white polymeric light-emitting diode was fabricated using Ir(PPOHC)₃ which showed a luminance efficiency of 15.3 cd/A, with CIE coordinates of (0.39, 0.44). These results indicate that the iridium complexes containing a linked carbazole-oxadiazole unit are promising candidates in high-efficiency electroluminescent devices.     

Hyperbranched triazine-containing polyfluorenes: Efficient blue emitters for polymer light-emitting diodes (PLEDs)

A series of hyperbranched triazine-containing polyfluorenes were synthesized by an “A₂ + A′₂ + B₃” approach based on Suzuki polycodensation. The polymers showed pure blue emission and the maximum emissions red-shifted in polar solvents and in solid film. By introducing triazine into polyfluorene, the electron injection and transport properties were improved and green emission was suppressed. PLED devices fabricated with the polymers showed reasonably high external quantum efficiencies.     

Deep blue light-emitting polymers with fluorinated backbone for enhanced color purity and efficiency

Two fluorene-based copolymers (PF-33F and PF-50F) with p-difluorophenylene units in the backbone were synthesized. In comparison with the reference poly(9,9-dioctylfluorene) (PFO), the introduction of p-difluorophenylene units not only increased the fluorescent quantum yields, but also improved the spectra purity and stability of these deep blue emitting copolymers. The famous green emission band at 520 nm from fluorenone defects was never detected for these copolymers even after they were thermal annealed in air at 150 °C. Organic light-emitting diodes were fabricated using them as emitting layer and pure blue electroluminescence was obtained. It was observed that PF-33F based device exhibited much higher current density and brightness than PF-50F and PFO devices. A maximum external quantum efficiency of 1.14% (1.14 cd A^?1) and the CIE (0.16, 0.13) were achieved for PF-33F device, which are among the best performance for polyfluorenes reported so far.     

Novel luminescent polymers containing backbone triphenylamine groups and pendant quinoxaline groups

Novel, conjugated polyfluorene derivatives that comprised an electron-donating triphenylamine group in the backbone and pendant, electron-accepting quinoxaline moieties, were synthesized via the Suzuki coupling reaction and their UV–vis absorption, fluorescence emission and electrochemical properties were investigated. The copolymers were readily soluble in common organic solvents and displayed good film-forming ability and excellent thermal stability. Electroluminescence devices, comprising indium tin oxide/poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonic acid)/emitting polymer/Ba/Al, in which the polymers were employed as emissive layers, exhibited superior performance compared to that of corresponding, poly(9,9-dioctylfluorene) and poly(9,9-dioctylfluorene-co-4,4′-triphenylamine) based devices, indicating that the polymers offer promise as emissive materials in polymeric light-emitting diodes.     

含1,3,4-噻二唑环氟取代苯基脲的合成及细胞分裂素活性

以取代肉桂酸和氨基硫脲为原料、以三氯氧磷为脱水剂经缩合-环化"一锅法"制备2-氨基-5-取代苯乙烯基-1,3,4-噻二唑,再与含氟苯甲酰基叠氮化物反应合成9种新的含氟取代苯基脲类化合物。其结构经红外光谱、核磁共振氢谱、质谱和元素分析所确认。初步的生物活性测试表明,目标化合物在10 mg/L浓度下表现出良好的细胞分裂素活性,促进率超过50%。     

Microwave assisted novel synthetic route for polyfluorenes containing triphenylamine and solubilizing alkyl moiety for blue emitting diodes

A series of blue electroluminescent polyfluorenes (PFs) containing triphenylamine and various alkyl moieties were synthesized using an Ni(0) mediated C?C Yamamoto coupling reaction assisted by microwaves. The synthesized PFs were characterized by various spectroscopic techniques. Their absorption and photoluminescence properties were investigated in solvent and found to possess characteristic electronic absorption and emission spectra. These PFs were found to emit in the blue region (407?415 nm) with high quantum yield in the range 0.41?0.73. Cyclic voltammetry studies of the PFs revealed that the compounds were stable under redox conditions with highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital in the range 5.24–5.29 eV and 1.98?2.01 eV, respectively. The E_HOMO for the PFs was similar to the most widely used hole transporting materials N,N′‐Di(1‐naphthyl)‐N,N′‐diphenyl‐(1,1′‐biphenyl)‐4,4′‐diamine (NPD), N,N′‐Bis(3‐methylphenyl)‐N,N′‐diphenylbenzidine (TPD) and N²,N²,N²′,N²′,N⁷,N⁷,N⁷′,N⁷′‐octakis(4‐methoxyphenyl)‐9,9′‐spirobi[9H‐ fluorene]‐2,2′,7,7′‐tetramine, Spiro‐OMeTAD (spiro‐OMe‐TAD). The thermal stability observed for the PFs accounts for their use under ambient conditions. The electrochemical studies of the fabricated polymer light emitting diodes suggest that the PFs have potential to be used as hole transporting and blue electroluminescent materials for optoelectronic devices. © 2017 Society of Chemical Industry     

An alternating copolymer for a blue light-emitting diode

An alternating copolymer composed of 9,9′-dihexylfluorene and N-2-ethylhexyl carbazole was synthesized to use as an emissive polymer in a light-emitting diode (LED). The copolymer is soluble in organic solvents and spin-cast to make a fine film. An LED fabricated by sandwiching the alternating copolymer between indium-tin oxide and aluminum emits a white color with the full width at half maximum of 150 nm. The electroluminescence spectrum becomes simplified to have an emission peak at 460 nm for fine blue color when the copolymer is blended with poly(vinylcarbazole) with a ratio of 1 to 4 before the use as an emissive layer. The forward bias turn-on voltage for the LED is 13, and quantum efficiency is 0.002%. Received: 21 October 1996/Revised: 6 November 1996/Accepted: 19 November 1996     

Photocrosslinkable hyperbranched polyfluorenes containing oxadiazole: synthesis,photophysics and electroluminescence

BACKGROUND: Crosslinkable hyperbranched polymers have great potential for use in organic light‐emitting devices and photovoltaics. With this in mind, two crosslinkable hyperbranched polyfluorenes, P5 and P6, containing oxadiazole as the core, and linear polyfluorene P0 were synthesized via palladium‐catalyzed Suzuki coupling. A device was also made. RESULTS: The resulting polymers were characterized using NMR, gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis. The spectral behavior of the polymers was also investigated. Compared with uncrosslinked P5 and P6, the photoluminescence spectra of crosslinked P5 and P6 were little influenced by the crosslinking. After annealing for 3 h at 200 °C in air, the photoluminescence of P6 (with a greater content of branched units) showed excellent stability compared with that of P5 and P0. The results for the device revealed that photocrosslinking improves the stability of the electroluminescence. CONCLUSION: The crosslinkable polymers obtained can be used in multilayer devices. Copyright © 2008 Society of Chemical Industry     

Novel carbazole/pyridine-based host material for solution-processed blue phosphorescent organic light-emitting devices

3,6-Bis(3,5-di(pyridin-3-yl)phenyl)-9-phenyl-9H-carbazole, a novel host material for solution-processed blue phosphorescent organic light-emitting devices was synthesized by a Suzuki coupling reaction. The optical, electrochemical and thermal properties of this novel crabazole have been characterized. The compound exhibits a high glass-transition temperature (Tg = 161 °C) and high triplet energy (E_T = 2.76 eV). Additionally, atomic force microscopy measurements indicate that high-quality amorphous films of this novel compound can be prepared by spin-coating. Solution-processed blue phosphorescent organic light-emitting devices were obtained using the carbazole as the host material for the phosphorescence emitter iridium(III) bis(4,6-difluorophenylpyridinato)- picolinate and their electroluminescence properties were evaluated.     

含1,3,4-(噁)二唑环的有机电致发蓝光材料及器件研究进展

1,3,4–口恶 二唑环是一个具有高电子亲和势和空穴阻挡作用的基团,含该基团的化合物是一类具有良好电子传输功能的有机电致发光材料。近年来含1,3,4–口恶 二唑环化合物发蓝光的有机电致发光材料已成为材料科学研究的一个热点。综述了含1,3,4–口恶 二唑环的小分子和高分子发蓝光的有机电致发光材料的分子结构、性能及其器件性能的研究现状,并对提高这类材料性能的分子设计方面作了简要的展望。     

Conjugated random and alternating 2,3,4,5-tetraphenylsilole-containing polyfluorenes: Synthesis, characterization, strong solution photoluminescence, and light-emitting diodes

A novel series of soluble conjugated random and alternating copolymers derived from 9,9-dioctylfluorene (FO) and 1,1-dimethyl-2,3,4,5-tetraphenylsilole (PSP) were synthesized by Suzuki coupling reactions. The feed ratios of FO to PSP were 95:5, 90:10, 85:15, 70:30, and 50:50. Chemical structures and optoelectronic properties of the copolymers were characterized by elemental analysis, NMR, UV absorption, cyclic voltammetry, photoluminescence (PL), and electroluminescence (EL). The elemental analyses of the copolymers indicated that FO and PSP contents in the copolymers were very close to that of the feed compositions. Unlike the weak PL emission of PSP small molecules in a solution, PFO-PSP solutions could emit strong lights with PL quantum yields between 13 and 30%, indicating that the incorporation of the PSP into the conjugated rigid main chain could greatly restrict the rotations of the phenyl groups of the PSP units even in a solution. Compared with the solution PL, complete PL excitation energy transfer from the PFO segments to the PSP units could be achieved by film PL at lower PSP content. The films of the copolymers exhibited high absolute PL quantum yields between 55 and 84%. EL devices with a configuration of ITO/PEDOT/PFO-PSP/Ba/Al demonstrated that the PSP units could serve as powerful exciton traps, giving exclusively pure green EL emissions. A maximum external quantum efficiency of 1.51% was achieved using the PFO-PSP15 as the emissive layer.     

Novel fluorene-based light-emitting copolymers containing cyanophenyl pendants and carbazole-triphenylamines: Synthesis, characterization and their PLED application

A series of novel blue light-emitting copolymers PCC-1, PCC-2, and PCC-3, composed of different ratios of electron-withdrawing segments (spirobifluorene substituted with cyanophenyl groups) and electron-donating segments (carbazole-triphenylamines), has been synthesized and characterized. In order to investigate the effect of hole/electron charge transporting segments, two reference polymers PSF and PCF, containing only one charge transporting moiety in the polymer backbone, were also synthesized. Incorporation of the rigid spirobifluorene units substituted with cyanophenyl groups into the polymer backbone improved not only the thermal stabilities but also the photoluminescence efficiencies. The polymers except PSF possess similar hole injection barriers but different hole transporting abilities. With the device configuration of ITO/PEDOT:PSS/polymers:PBD/CsF/Ca/Al, PCC-2 showed the best performance with the lowest turn-on voltage of 3.1 V, the highest luminance of 6369 cd/m², the highest current efficiency of 1.97 cd/A, and the best power efficiency of 1.40 lm/w.     

Electron-withdrawing groups and strong-field ligands containing iridium(III) complexes and their efficient blue light-emitting

Two new heteroleptic iridium(III) complexes [Ir(4,6-dfppy)₂(PPh₃)L] (4,6-dfppy = 2-(4,6-difluorophenyl)pyridyl, PPh₃ = triphenylphosphine, L = NCS^?, 1; NCO^?, 2) have been synthesized and fully characterized. By introduction of electron-withdrawing groups such as fluorine atoms on the 4- and 6-positions of 2-phenylpyridyl (ppy) and using strong-field ligands for instance PPh₃ and pseudohalogen as ancillary ligands, the HOMO–LUMO electronic energy gaps of 1 and 2 have been increased sufficiently. The photoluminescence (PL) spectra of 1 and 2 in solution show emission maxima at 456 and 458 nm, respectively, corresponding to efficient blue light-emitting. X-ray analyses show that intra- and intermolecular π–π interactions exist in the solid state of 1 and 2. The PL spectra of 1 and 2 in solid state exhibit about 30 nm spectral red shifts compared with those in solution.     

含喹喔啉环1,3,4- 二唑衍生物的合成及结构鉴定

报道了果糖与邻苯二胺反应制得喹喔啉－２－甲醛后,与芳酰肼作用得到相应的芳酰腙,芳酰腙在不同的条件下环化分别得到１,３,４－恶二唑衍生物,产物经元素分析、ＩＲ、＾１ＨＮＲ和ＭＳ确证了其结构。     

Novel, water-based fluorinated polymers with excellent antigraffiti properties

In this article we describe novel, water-based, crosslinkable fluorinated polymers that form coatings with excellent antigraffiti properties. The synthesis of the binders and the surface and bulk properties of their coatings are discussed. The surface properties of these coatings are characterized in terms of their surface-free energy, as calculated from static contact angle measurements. The distribution of the fluorine atoms throughout the coating is measured by X-ray photoelectron spectroscopy (XPS). The bulk properties are studied by determining the crosslink density through dynamic mechanical thermal analysis (DMTA), and the effect of the crosslinking conditions on the crosslink density and the antigraffiti properties is discussed. The results indicate that a combined action of surface and bulk properties gives these coatings their excellent antigraffiti properties. The applicability of these polymers as protective coatings for metal and concrete surfaces are demonstrated. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL     

Fabrication of red, green, and blue organic light-emitting diodes using m-MTDATA as a common hole-injection layer

Organic light-emitting diodes (OLEDs) of metal-semiconductor-metal (MSM) structure have been fabricated by using m-MTDATA [4,4′,4′’-tris (3-methylphenylphenylamino) triphenylamine] as a hole-injection layer (HIL). The m-MTDATA is shown to be an effective hole-injecting material for the OLED, in that the insertion of m-MTDATA greatly reduces the roughness of anode surface, lowers the turn-on voltage, and increases the luminous efficiency. Red, green and blue OLEDs were fabricated, and their color coordinates in CIE chromaticity were found to be (0.600, 0.389), (0.240, 0.525) and (0.171, 0.171), respectively. The luminous efficiencies of the fabricated OLEDs were 1.4 lm/W at 106 cd/m² for red, 1.4 lm/W at 100 cd/m² for green, and 2.0 lm/W at 104 cd/m² for blue.     

Synthesis and properties of poly(p-phenylenevinylene-co-sulfonylene) for a blue light-emitting diode

Summary Novel class of p-phenylenevinylene copolymer with sulfonylene group in the main chain (PPVS) was synthesized through the Wittig reaction of bis(bromomethyl-p-phenyl)-sulfone triphenylphosphonium salt with terephthaldehyde. PPVS was highly soluble in common organic solvents and showed strong blue-shifted fluorescence because the polar sulfonylene group provided better solubility and limited π-conjugation in polymer chain. A single layer device with PPVS sandwiched between indium-tin-oxide (ITO) and aluminum electrodes showed a blue electroluminescence (EL) peaked at 470 nm under the threshold voltage of 14 V. HOMO and LUMO levels of PPVS were found to be 0.46 and 0.28 eV, respectively, lower than those of poly(p-phenylenevinylene) (PPV). Received: 20 April 1999/Revised version: 31 May 1999/Accepted: 28 June 1999     

Novel poly(arylene ethynylene) derivatives containing main chain triphenylamine and pendent quinoxaline moieties: synthesis and elementary characterization

BACKGROUND: Various poly(arylene ethynylene)s (PAEs) have been prepared and applied as molecular wires, in sensors, in nonlinear optics and as electroluminescent materials. But, to our knowledge, there has been no attention paid to the investigation of conjugated PAEs containing both triarylamine and quinoxaline groups. The influence imparted by the introduction of triarylamine and quinoxaline on the photophysical and electrochemical properties of PAEs is of interest. RESULTS: Two kinds of novel PAE derivatives, with electron‐donating triphenylamine groups in the backbone and electron‐accepting pendent quinoxaline moieties and bearing side chains of different lengths, were successfully synthesized with the Sonogashira coupling reaction. These polymers are soluble in common organic solvents and exhibit good film‐forming ability and thermal stability. UV‐visible investigations indicate that the ground states of these materials are unaffected by the polarity of their medium. An efficient intramolecular charge transfer effect is observed from an investigation of their photoluminescence properties in different solvents. Cyclic voltammetry study reveals that these polymers possess relatively high highest occupied molecular orbital levels due to the incorporation of triphenylamine segments into the polymer backbones. CONCLUSION: Primary characterization of these novel PAE derivatives shows that they might serve as potential active materials in optoelectronic devices. Copyright © 2009 Society of Chemical Industry