Preparation of New Electron-Accepting π-Conjugated Polyquinoxalines. Chemical and Electrochemical Reduction, Electrically Conducting Properties, and Use in Light-Emitting Diodes

Yamamoto, Takakazu; Sugiyama, K.; Kushida, Takashi; Inoue, Tetsuji; Kanbara, Takaki

doi:10.1021/ja954173d

Cited by 206 publications

(130 citation statements)

References 49 publications

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“…The subsequent recombination of holes and electrons occurs in the PPV layer. In contradiction to some published results using quinoxaline units as HBETLs, we do not observe any emission from the p-QUX layer [22,36,37]. The reduced current densities can be explained by high oxidation potentials of our HBETL polymers leading to a higher hole blocking barrier at the PPV/HBETL interface, preventing unipolar hole current flow.…”

Section: Led Resultscontrasting

confidence: 99%

A comparison of hole blocking/electron transport polymers in organic LEDs

et al. 1998

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Three main‐chain aromatic polyethers with different electroactive heterocyclic moieties, 1,4‐quinoxaline, 1,3,4‐oxadiazole and 1,3,5‐triazine, have been synthesized. The polymers are amorphous with glass transition temperatures above 200°C. The polymers with these high electron affinity units were used as hole blocking/electron transport layers (HBETL) in light‐emitting diodes (LEDs) having the HBETL casted on top of a hole transport/emitting PPV layer. In order to compare the influence of the different polyethers on the LED characteristics, three multilayer devices (ITO/PPV/HBETL/Al) with different HBETLs were investigated. Relative to the single layer PPV device, quantum efficiencies were improved by two orders of magnitude in all multilayer devices and power efficiency was increased using poly(quinoxaline ether) as HBETL. To investigate the electrochemical behavior of the three HBETLs, cyclic voltammetry measurements were carried out and the HOMO/LUMO energy values determined from redox potentials were used to understand the hole blocking property. Lowering the onset voltage using the poly(quinoxaline ether) as HBETL in two‐layer devices is compatible with the high electron affinity of this polymer.

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Section: Led Resultscontrasting

confidence: 99%

A comparison of hole blocking/electron transport polymers in organic LEDs

et al. 1998

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“…Other six-membered ring poly(arylene)s with imine(s) nitrogen(s) having electron acceptor properties are poly-(pyrimidine) (66) [152], polyquinoline (67) [153], poly-(quinoxaline-5,8-diyl) (68) [154,155] or poly(quinoxaline-2,6-diyl) (69) [153]. Among them, it is worth mentioning the use of polyquinoxalines as electron injecting material for electroluminescent devices [153].…”

Section: Modification Of Electronic Properties Of Conjugated Polymersmentioning

confidence: 99%

The chemistry of electroluminescent organic materials

Segura¹

1998

Acta Polym.

287

200

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Electroluminescence has been a subject of interest for several decades because of its many applications in areas such as telecommunications or information displays. Light‐emitting diodes using p‐n junctions of inorganic semiconductors have dominated the field in the last twenty years; however, efficient blue emission has only recently been achieved and inorganic semiconductors are difficult to form over large areas, making the process uneconomic. During the last decade, an explosive growth of activity in the area of organic electroluminescence has occurred in both academia and industry, stimulated by the promise of light‐emitting plastics for the fabrication of large, flexible, inexpensive and efficient screens to be used in different applications. Thus, a substantial amount of research is presently directed towards color control and improvement of manufacturability and reliability of devices in order to make their commercialization viable. A great deal of work has been carried out by physicists and materials scientists concerned with the preparation of different device structures and with the use of different techniques for device manufacture. However, all this work would not be possible without the continuous efforts of synthetic chemists to prepare materials with enhanced luminescent properties and processabilities. This article provides a review of the main types of organic materials that have been used in the fabrica‐tion of light‐emitting diodes either as emitting materials or as charge‐transport layers. Special attention will be paid to the different synthetic strategies that have been followed in order to tune the color of the emission, to increase stability of materials and to enhance their processabilities.

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“…Fluorescent heterocyclic dyes whose fluorescence emission occurs at red wavelengths are expected to play a leading role in full color electroluminescence displays [2e7]. Several quinoxaline derivatives as well as heterocycles that contain a quinoxaline moiety have p-extended frameworks and are much used as photoluminesent molecules [8e10] and electron-transport materials in multilayer OLEDs [11,12]. For use in LEDs, a knowledge of the photophysical characteristics of the charge-transporting materials is of fundamental importance in terms of the optimisation of device properties and is also valuable for the design of potential new blue-light emitters [13].…”

Section: Introductionmentioning

confidence: 99%

The tautomerism, solvatochromism and non-linear optical properties of fluorescent 3-hydroxyquinoxaline-2-carboxalidine-4-aminoantipyrine

et al. 2010

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a b s t r a c tThe Schiff base, 3-hydroxyquinoxaline-2-carboxalidine-4-aminoantipyrine, was synthesized by the condensation of 3-hydroxyquinoxaline-2-carboxaldehyde with 4-aminoantipyrine. HPLC, FT-IR and NMR spectral data revealed that the compound exists predominantly in the amide tautomeric form and exhibits both absorption and fluorescence solvatochromism, large stokes shift, two electron quasireversible redox behaviour and good thermal stability, with a glass transition temperature of 104 C. The third-order non-linear optical character was studied using open aperture Z-scan methodology employing 7 ns pulses at 532 nm. The third-order non-linear absorption coefficient, b, was 1.48 Â 10 À6 cm W À1 and the imaginary part of the third-order non-linear optical susceptibility, Im c (3) , was 3.36 Â 10 À10 esu. The optical limiting threshold for the compound was found to be 340 MW cm À2 .

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Preparation of New Electron-Accepting π-Conjugated Polyquinoxalines. Chemical and Electrochemical Reduction, Electrically Conducting Properties, and Use in Light-Emitting Diodes

Cited by 206 publications

References 49 publications

A comparison of hole blocking/electron transport polymers in organic LEDs

A comparison of hole blocking/electron transport polymers in organic LEDs

The chemistry of electroluminescent organic materials

The tautomerism, solvatochromism and non-linear optical properties of fluorescent 3-hydroxyquinoxaline-2-carboxalidine-4-aminoantipyrine

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