Novel fluorine containing polyfluorenes with efficient blue electroluminescence

Assaka, Andressa M.; Rodrigues, Paula C.; Oliveira, Alfredo R. M. de; Ding, Liming; Hu, Bin; Karasz, Frank E.; Akcelrud, Leni

doi:10.1016/j.polymer.2004.07.072

Cited by 61 publications

(40 citation statements)

References 40 publications

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“…And the peaks of δ 140.68, δ 140.17, and δ 126.35 were assigned to the C-11(12), C-3(6), and C-2(7) of the fluorene ring, respectively. The concise peaks of 13 C NMR spectrum indicated that in Polymer B the fluorene moieties linkage at 2, 7′-position with good region-regularity, which agreed with the polyfluorenes obtained by the typical Suzuki coupling polymerization [13] .…”

Section: Nuclear Magnetic Resonance Analysis Of the Polymerssupporting

confidence: 80%

“…(a) 1 H NMR；(b) 13 C NMR However, the 13 C NMR spectra of the other polymers except Polymer B show less region-regularity. In Fig.5, Polymer C and D display peaks at δ 127.02, δ 123.15 respectively, while Polymer A and E display the peaks at δ 127.21, δ 124.65, and additional signals at δ 141.04, δ 140.98.…”

Section: Fig 4 the Aromatic Region Of The Nmr Spectra Of Polymer B Imentioning

confidence: 99%

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Green light-emitting region-regular poly(9,9-dihexylfluorene-co-fluorenone) prepared from solvent-free oxidative coupling polymerization

Zhan

Chen

Bai

et al. 2007

Wuhan Univ. J. of Nat. Sci.

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Soluble green light-emitting poly(9,9-dihexylfluoreneco-fluorenone) was synthesized by solvent-free oxidative coupling polymerization of 9,9-dihexylfluorene in a facile one-step reaction. The polymers were characterized by FT-IR, 1 H NMR, 13 C NMR, UV-Vis and fluorescence spectroscopy. The region-regular structure of the polymer linking at 2, 7′-position on the fluorene moieties was obtained. The FT-IR spectra of the polymers showed fluorenone vibration. The fluorescence spectra of the solid thin film of the polymers displayed green light-emitting, which was emitted from fluorenone moieties produced in the polymerization process.Because of good optical property and high luminescent efficiencies [1,2] , poly (9, 9-dialkylfluorene)s have received a lot of attention [3] , attributed to the possibility to develop all plastic, full color light-emitting diodes [4] . An important driving force for this research is the possibility of building ultra thin and flexible screens for computers and televisions. The facile substitution at the remote 9-position provides the possibility of improving the solubility and processability of the polymers without significantly increasing the steric interactions in the polymer backbone. Remote substitution also offers the possibility of controlling interchain interactions, which can lead to excimer formation in the excited state. As examples of π-conjugated polymers, poly(dihexylfluorene) (PDHF) derivatives are particular suitable blue light-emitting materials because they contain rigid biphenyl units with wide band gap and efficient blue emission [5] .The first transition-metal catalyzed coupling of 2, 7-dibromo-9, 9-dialkylfluorenes with Ni(Ⅱ) salt/Zn was described by Pei [1] . Later, Ranger [6] reported the synthesis of poly(9, 9-dialkylfluorene) following the Suzuki-type cross-coupling polymerization. The Yamamoto reaction also was used to prepare well-defined fluorene oligomers and polymers [7,8] . However there are some shortcomings such as complicated procedures, high cost, or expensive noble metal as catalyst.

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Section: Nuclear Magnetic Resonance Analysis Of the Polymerssupporting

confidence: 80%

Section: Fig 4 the Aromatic Region Of The Nmr Spectra Of Polymer B Imentioning

confidence: 99%

Green light-emitting region-regular poly(9,9-dihexylfluorene-co-fluorenone) prepared from solvent-free oxidative coupling polymerization

Zhan

Chen

Bai

et al. 2007

Wuhan Univ. J. of Nat. Sci.

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“…The choice of a polyfluorene for the main component was based on the fact that this class of polymer has emerged as an important class of blue emitter, with intense photoluminescence, good charge transport and thermal stability properties [23][24][25][26]. The other components, all of them also electroluminescent in a different spectral range, were chosen as an attempt to achieve white light emission.…”

Section: Introductionmentioning

confidence: 99%

Polyfluorene based blends for white light emission

Deus

Faria²,

Iamazaki

et al. 2011

Organic Electronics

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“…Lifetime measurement confirms this assignment. The electroluminescence spectrum reported 32 for this polymer displayed a spectrum similar to that of photoluminescence, showing that the exciton recombination produces an isolated fluorenyl group in the excited state which emits in the bluerange of the visible spectrum. Theoretical calculations showed that the persistent length of the fluorenyl units involved with the emission becomes invariant between 6-7 mers.…”

Section: Discussionmentioning

confidence: 58%

“…Poly(2,7-9,9'-dihexylfluorene-dyil) (PHF) was synthesized by according the protocol described elsewhere. 1,32 Molecular weight was determined as M -n = 8500 g mol -1 and polydispersity of 1.4 by gel permeation chromatography.…”

Section: Methodsmentioning

confidence: 99%

Photophysical properties and quantum chemical studies of poly(2,7-9,9'-dihexylfluorene-dyil)

Oliveira¹,

Martins²,

Honório³

et al. 2009

J. Braz. Chem. Soc.

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Este trabalho descreve as propriedades fotofísicas (espectros de excitação e de fluorescência, rendimento quântico e tempo de meia-vida de fluorescência) do poli(2,7-9,9'diexil-fluoreno-diil) em soluções diluídas, de quatro solventes (tolueno, tetraidrofurano, clorofórmio e acetato de etila) e no estado sólido. Os espectros de fotoluminescência são característicos da conformação desordenada da cadeia principal, denominada forma α. Espectros eletrônicos de absorção foram simulados para oligômeros de 1 a 11 meros, indicando que o comprimento crítico de conjugação está entre 6 e 7 meros. Os valores teóricos do momento de dipolo mostraram que a conformação helicoidal formada se repete a cada 8 unidades por volta. Mostra-se ainda que no estado sólido ocorrem processos de transferência de energia que levam a uma diminuição do tempo de meia-vida de fluorescência. Com base nos espectros obtidos, pode-se concluir que a fotoluminescência e a eletroluminescência descrita na literatura são provenientes das mesmas unidades emissoras.This work reports the photophysical properties (excitation and fluorescence spectra, fluorescence quantum yield, fluorescence lifetimes) of the poly(2,7-9,9'-dihexylfluorene-dyil) in dilute solutions of four solvents (toluene, tetrahydrofuran, chloroform and ethyl acetate) as well as the properties in solid state. Photoluminescence showed spectra characteristic of disordered α-backbone chain conformation. Simulation of the electronic absorption spectra of oligomers containing 1 to 11 mers showed that the critical conjugation length is between 6 and 7 mers. We also estimated the theoretical dipole moments which indicated that a coil conformation is formed with 8 repeating units per turn. We also showed that some energy transfer process appears in solid state which decreases the emission lifetime. Furthermore, based on luminescent response of the systems herein studied and electroluminescent behavior reported on literature, both photo and electroluminescence emissions arise from the same emissive units.Keywords: polyfluorene, photophysical properties, quantum mechanical calculation, photoluminescence IntroductionPolyfluorene and derivates form a class of conjugated polymers whose photoluminescence emission is strongly dependent on their chemical structure ranging from the violet to red.1-8 Several of them are also electroluminescent materials.1,4-9 The backbone of fluorene-based polymers contains a rigidly planar biphenyl structure which can be functionalized in the C-9 position to enhance the polymer solubility. Nevertheless, this substitution at C-9 induces minor steric effects in the adjacent aromatic rings, 10 leading, in general, to small geometrical disturbance. It is also well known that some polyfluorenes in solid state may form liquid-crystalline phases, with high ordered crystalline phases with thermotropic phase transition from 100 to 170 °C.11 Moreover, the polymer chain may be organized in the solid state undergoing phase structure with different spectral properties: more ordered α-pha...

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Novel fluorine containing polyfluorenes with efficient blue electroluminescence

Cited by 61 publications

References 40 publications

Green light-emitting region-regular poly(9,9-dihexylfluorene-co-fluorenone) prepared from solvent-free oxidative coupling polymerization

Green light-emitting region-regular poly(9,9-dihexylfluorene-co-fluorenone) prepared from solvent-free oxidative coupling polymerization

Polyfluorene based blends for white light emission

Photophysical properties and quantum chemical studies of poly(2,7-9,9'-dihexylfluorene-dyil)

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