Copolyfluorenes containing bridged triphenylamine or triphenylamine: Synthesis, characterization, and optoelectronic properties
TL;DR: Aryl-bridged triphenylamine derivative, 7-tbutyl-5,5,9,9-tetraaryl-13b-aza-naphtho[3,2,1-de]anthracene (ABTPA) was designed and synthesized as mentioned in this paper.
Abstract: A novel aryl-bridged triphenylamine derivative, 7-t-butyl-5,5,9,9-tetraaryl-13b-aza-naphtho[3,2,1-de]anthracene (ABTPA) was designed and synthesized. The alternating copolymers of ABTPA/dihexylfluorene (P1) and triphenylamine (TPA)/dihexylfluorene (P2) were synthesized by Suzuki coupling reaction. P1 shows excellent thermal stability with a decomposition temperature of 440 °C and a glass-transition temperature of 326 °C. The HOMO energy levels of the two polymers are very close (−5.15 eV for P1 and −5.13 eV for P2). The maximum absorption peak of P1 is red shifted by 23 nm with respect to P2, because the incorporation of ABTPA units into the PF backbone enhances the electronic conjugation degree compared with the case of TPA units. The rigidity and the steric hindrance of the ABTPA in P1 result in a small Stokes shift and almost the same emission spectra of P1 between its film and solution. A PLED with simple configurations of ITO/P1/TNS (tetranaphthalen-2-yl-silane)/Alq3 (tris(8-hydroxyquinolinolato)aluminum)/Al emits a blue light with emission peak at 436 nm, and exhibits a maximum current efficiency of 1.89 cd/A and a maximum luminance of 4183 cd/m2, which is superior to the device with P2 as emissive layer under the identical conditions. These results indicate that ABTPA unit could be a very promising candidate to replace TPA unit and find widely application in organic/polymeric optoelectronic materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3651–3661, 2009
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TL;DR: The experimental results indicate that the multifraction structure leads to a significant fluorescence enhancement (over two times) compared to the monomer, which might be attributed to the formation of delocalized excited state in multibranch structures.
Abstract: Five novel organic conjugated derivatives containing multifraction twisted acene units have been synthesized and characterized. These compounds and the model molecule 2-methyl-5,12-diphenyl-6:7,10:11-bisbenzotetracene emit strong blue light in diluted solution with quantum yields of 0.21–0.67, while in the solid state, except for the 1,2,3,4,5,6-hexa(2-(5,12-diphenyl-6:7,10:11-bis(4′-tert-butylbenzo)tetracene))benzene, green luminance is seen. The experimental results also indicate that the multifraction structure leads to a significant fluorescence enhancement (over two times) compared to the monomer, which might be attributed to the formation of delocalized excited state in multibranch structures. The quantum-chemical calculation implies that only two branches are involved in formation of the delocalized system for the multibranched derivatives. Furthermore, the organic light-emitting diode (OLED) devices using compounds 1,4-di(2-(5,12-diphenyl-6:7,10:11-bis(4′-tert-butylbenzo)tetracene))benzene, 1,3-di...
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TL;DR: A series of n-type hexaazatriphenylene derivatives synthesized by condensation coupling of 1,2-diamines and 1, 2-diketones showed that their lowest unoccupied molecular orbital (LUMO) energy levels could be effectively tuned from -3.54 to -4.02 eV simply by increasing the number of pyrazine units in their molecular structures.
35 citations
TL;DR: A triphenylamine-based aromatic dicarboxylic acid monomer was synthesized from the cesium fluoride mediated N,N-diary-lation reaction of 4-tert-butylaniline with 4-fluorobenzonitrile and subsequent alkaline hydrolysis of the dinitrile intermedi- ate as discussed by the authors.
Abstract: A new triphenylamine-based aromatic dicarboxylic acid monomer, 4-tert-butyl-4 0 ,4 00 -dicarboxytriphenylamine (2), was synthesized from the cesium fluoride mediated N,N-diary- lation reaction of 4-tert-butylaniline with 4-fluorobenzonitrile and subsequent alkaline hydrolysis of the dinitrile intermedi- ate. A series of six aromatic polyamides 4a-4f with tert-butyltri- phenylamine groups was prepared from the newly synthesized dicarboxylic acid and various aromatic diamines. These polya- mides were readily soluble in many organic solvents and could be solution-cast into flexible and strong films. The glass-transi- tion temperatures of these polymers were in the range of 274- 311 � C. These polymers exhibited strong UV-vis absorption bands at 356-366 nm in NMP solution. Their photolumines- cence spectra showed maximum bands around 433-466 nm in the blue region. Cyclic voltammograms of all the polyamides exhibited reversible oxidation redox couples in acetonitrile. The polyamide 4f, with tert-butyltriphenylamine segment in both diacid and diamine residues, exhibited stable electrochro- mic characteristics with a color change from a colorless neutral form, through a green semioxidized form, to a deep purple fully oxidized form. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2798-2809, 2010
29 citations
TL;DR: In this paper, a series of conjugated blue-light-emitting copolymers (PTC-1, PTC-2, and pTC-3) comprised different ratios of electronwithdrawing segments (spirobifluorene substituted with cyanophenyl groups) and electron-donating segments (tricarbazole-triphenylamines), has been synthesized.
Abstract: A series of conjugated blue-light-emitting copolymers, PTC-1, PTC-2, and PTC-3, comprised different ratios of electron-withdrawing segments (spirobifluorene substituted with cyanophenyl groups) and electron-donating segments (tricarbazole-triphenylamines), has been synthesized. The structures of these polymers were characterized and their thermal, photophysical, electrochemical, and electroluminescence properties were measured. Incorporation of rigid spirobifluorene units into the copolymers led to blue-shifted absorption peaks in dilute toluene solution. Cyclic voltammetric measurement indicated the bandgaps of the polymers were in the range of 2.77-2.94 eV. It was found that increasing cyanophenyl-spirobifluorene content in the polymer backbone lowered both the HOMO and LUMO energy levels of the copolymers, which was beneficial for electron injection/transporting in the polymer layer of the device. OLED device evaluation indicated that all the polymers emitted sky blue to deep blue light when the pure polymers were used as the emissive layers in the devices with a configuration of ITO/PEDOT:PSS/polymers/CsF/Ca/Al. The devices have been optimized by doping 30 wt % PBD into the polymer layers. Among the doped devices, PTC-2 showed the best performance with the turn-on voltage of 3.0 V, maximum brightness of 7257 cd/m(2), maximum current efficiency of 1.76 cd/A, and CIE coordinates of (0.15, 0.14). (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 292-301, 2010
25 citations
TL;DR: In this paper, bipolar copoly(p-phenylene)s with bipolar groups were synthesized to enhance electroluminescence (EL) of poly(pphenylene vinylene) (PPV) derivatives.
Abstract: Two novel copoly(p-phenylene)s (P1–P2) containing bipolar groups (12.8 and 6.8 mol %, respectively), directly linked hole transporting triphenylamine and electron transporting aromatic 1,2,4-triazole, were synthesized to enhance electroluminescence (EL) of poly(p-phenylene vinylene) (PPV) derivatives. The bipolar groups not only enhance thermal stability but also promote electron affinity and hole affinity of the resulting copoly(p-phenylene)s. Blending the bipolar copoly-(p-phenylene)s (P1–P2) with PPV derivatives (d6-PPV) as an emitting layer effectively improve the emission efficiency of its electroluminescent devices [indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene) (PEDOT):poly(styrenesulfonate) (PSS)/polymer blend/Ca (50 nm)/Al (100 nm)]. The maximum luminance and maximum luminance efficiency were significantly enhanced from 310 cd m−2 and 0.03 cd A−1 (d6-PPV-based device) to 1450 cd m−2 and 0.20 cd A−1 (blend device with d6-PPV/P1 = 96/4 containing ∼0.5 wt % of bipolar groups), respectively. Our results demonstrate the efficacy of the copoly(p-phenylene)s with bipolar groups in enhancing EL of PPV derivatives. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
24 citations
References
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TL;DR: In this article, the authors demonstrate that poly(p-phenylene vinylene), prepared by way of a solution-processable precursor, can be used as the active element in a large-area light-emitting diode.
Abstract: CONJUGATED polymers are organic semiconductors, the semiconducting behaviour being associated with the π molecular orbitals delocalized along the polymer chain. Their main advantage over non-polymeric organic semiconductors is the possibility of processing the polymer to form useful and robust structures. The response of the system to electronic excitation is nonlinear—the injection of an electron and a hole on the conjugated chain can lead to a self-localized excited state which can then decay radiatively, suggesting the possibility of using these materials in electroluminescent devices. We demonstrate here that poly(p-phenylene vinylene), prepared by way of a solution-processable precursor, can be used as the active element in a large-area light-emitting diode. The combination of good structural properties of this polymer, its ease of fabrication, and light emission in the green–yellow part of the spectrum with reasonably high efficiency, suggest that the polymer can be used for the development of large-area light-emitting displays.
10,463 citations
1,485 citations
TL;DR: In this article, the particular properties of soluble derivatives of polyfluorene homopolymers with respect to emission properties, control of color stability and efficiency in electroluminescence, alignment in thin layers and polarized emission are discussed.
Abstract: Since the first report on blue electroluminescence from a soluble poly(9,9-di-alkylfluorene), fluorene-based homo- and copolymers have evolved as a major class of polymeric emitters for highly efficient organic light-emitting diodes. This Review is concerned with the particular properties of soluble derivatives of polyfluorene homopolymers with respect to emission properties, control of color stability and efficiency in electroluminescence, alignment in thin layers and polarized emission. A major point of discussion is the origin of unwanted emission contributions in the photoluminescence and electroluminescence spectra of solid layers as well as concepts to avoid these contributions in order to ensure stable device performance. Further, the alignment of polyfluorenes and their use in polarized light-emitting diodes is addressed.
787 citations
TL;DR: In this paper, a white light-emitting electroluminescent devices were fabricated using poly(Nvinylcarbazole) (PVK) as a hole-transporting emitter layer and a double layer of 1,2,4−triazole derivative (TAZ) and tris(8quinolinolato)aluminum(III) complex (Alq) as an electron transport layer.
Abstract: White light‐emitting electroluminescent devices were fabricated using poly(N‐vinylcarbazole) (PVK) as a hole‐transporting emitter layer and a double layer of 1,2,4‐triazole derivative (TAZ) and tris(8‐quinolinolato)aluminum(III) complex (Alq) as an electron transport layer. The PVK layer was doped with fluorescent dyes such as blue‐emitting 1,1,4,4‐tetraphenyl‐1,3‐butadiene, green‐emitting coumarin 6, and orange‐emitting DCM 1. A cell structure of glass substrate/indium‐tin‐oxide/doped PVK/TAZ/Alq/Mg:Ag was employed. White emission covering a wide range of the visible region and a high luminance of 3400 cd/m2 were obtained at a drive voltage of 14 V.
778 citations
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