- Synthesis, solid-phase reaction, optical properties, and patterning of luminescent polyfluorenes
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The homopolymer of 9,9-di(2-(2-tetrahydropyranyloxy)ethyl)fluorene and copolymers based on 9,9-dihexylfluorene, thiophene, and 3-(2-(2- tetrahydropyranyloxy)ethyl)thiophene repeat units were obtained as patternable blue, green, and blue-green color luminescent polymers. Thermolytic and acid-catalyzed removal of the bulky tetrahydropyran (THP) group from thin solid films of the polymers was investigated. The acid-catalyzed deprotection can be carried out at a significantly lower temperature than thermolytic deprotection in the absence of acid. The effect of the acid-catalyzed deprotection of these polyfluorenes (PFs) on the photoluminescent properties was studied. Prior to deprotection, the polyfluorenes show good optical properties and high emission intensity both in solution and in the solid state. After deprotection, their optical properties were retained and their quantum yields of photoluminescence remained high, but their solubility was reduced due to the presence of hydroxyl groups. The decrease in solubility allows for their spatially controlled deposition using chemically amplified soft lithography.
- Han, Xu,Chen, Xiwen,Vamvounis, George,Holdcroft, Steven
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- Stabilized blue luminescent polyfluorenes: Introducing polyhedral oligomeric silsesquioxane
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A new POSS (polyhedral oligomeric silsesquioxane)-substituted polyfluorene was synthesized from the nickel-catalyzed Yamamoto coupling reaction. The synthesized polymers could be well characterized by 1H NMR, FT-IR, and elemental analysis. PL spectra of PFPOSSs on the quartz film showed reduced aggregation/excimer formation because the bulky POSS group prohibited interchain interactions. This effective dilution effect and the high thermal stability of the POSS unit also improved the color stability of PFPOSSs blue emission even after thermal annealing at 150°C. The fluorescence quantum yields (ΘFL) of PFPOSSs in both solution and solid state were higher than those of poly(dialkylfluorene)s. Moreover, the ITO/PEDOT-PSS/polymer/Ca/Al LED device using this polymer as emitting layer showed a very stable blue light emission. LED devices of PFPOSSs showed a low turn-on voltage of 3.7-4.4 V, high brightness of 350-1010 cd/m2, and external efficiencies of 0.11-0.36%.
- Lee, Jonghee,Cho, Hoon-Je,Jung, Byung-Jun,Cho, Nam Sung,Shim, Hong-Ku
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- Fluorene-containing polyhedral oligomericsilsesquioxanes modified hyperbranched polymer for white light-emitting diodes with ultra-high color rendering index of 96
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In this work, a series of hyperbranched white-emitting conjugated polymers were synthesized with polyfluorene (PF) as the branches and three-dimensional-structured spiro[3.3]heptane-2,6-dispirofluorene (SDF) as the conjugated branching point by one-pot Suzuki polycondensation, where 4,7-dithienyl-2,1,3-benzothiadiazole (DBT) as orange-light emitting unit and fluorene-containing polyhedral oligomericsilsesquioxanes (POSSs) as conjugated linking monomer were introduced into the backbones to obtain white-light emission. The influence mechanism of POSSs for hyperbranched white-emitting polymers was explored by adjusting the feeding ratios of fluorene-containing POSSs (from 1 to 20 ?mol%). The results indicated that the synthesized polymers still maintained the high thermal stabilities, and exhibited the improved amorphous film morphology and hydrophobicity, which were beneficial for obtaining optimized interface between the aqueous hole transport layer Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) layer and polymer light-emitting layer in device fabrication. As a consequence, all of the fabricated devices with the hyperbranched polymers as light-emitting layers realized white light-emission, and the optimized device exhibite good electroluminescent (EL) performance with Commission Internationale de l'Eclairage (CIE) coordinates at (0.32, 0.33) and maximum color rendering index (CRI) of 96. The fluorene-containing POSSs modified hyperbranched copolymers with broad full width at half maximum (>284 ?nm) are attractive candidates for sunlight-style white polymer light-emitting diodes.
- Wang, Mixue,Wei, Xiaozhen,Zhang, Weixuan,Zhao, Haocheng,Wu, Yuling,Miao, Yanqin,Wang, Hua,Xu, Bingshe
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- Solubility modulation of polyfluorene emitters by thermally induced (retro)-diels-alder cross-linking of cyclopentadienyl substituents
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For cost-efficient organic electronic devices, the consecutive deposition of active layers by solution-based processes is a key benefit. We report a synthetic approach enabling solubility reduction of bis(cyclopentadienyl)- substituted polyfluorenes as emissive layers in organic light-emitting diodes (OLEDs). Thermally induced retro-Diels-Alder reaction liberates free cyclopentadiene as "protecting group" and pending cyclopentadienyl units, which crosslink the polymer strands upon cooling via [4+2] cycloadditions. The activation temperature is tuned in the range of 180-250°C through alkyl, alkoxy, or ester linkages. Ultimately, macrocyclic self-protected bis(cyclopentadienylene) moieties avoid extrusion of volatile cyclopentadiene during activation. The solvent resistance of the emissive layers after cross-linking is examined by absorption spectroscopy and white light scanning interferometry. The influence of the desolubilization procedure on the performance of solution-processed OLEDs is investigated.
- Ahrens, Lukas,Schlisske, Stefan,Strunk, Karl-Philipp,Hinkel, Felix,Melzer, Christian,Bunz, Uwe H.F.,Lemmer, Uli,Hernandez-Sosa, Gerardo,J?nsch, Daniel,Freudenberg, Jan,Müllen, Klaus
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p. 4157 - 4167
(2018/06/11)
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- PHOTOREACTIVE COMPOUND, LIQUID CRYSTAL ALIGNMENT LAYER USING THE COMPOUND, METHOD OF MANUFACTURING THE ALIGNMENT LAYER, AND LIQUID CRYSTAL DISPLAY DEVICE CONTAINING THE ALIGNMENT LAYER
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Provided are a photoreactive compound represented by formula (1) in the description and the claims, a liquid crystal alignment layer using the compound, a method of manufacturing the alignment layer, and a liquid crystal display device including the alignment layer.
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Page/Page column 8
(2008/06/13)
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