Heterolayer light-emitting diodes based on new oxadiazole polymers

Meier, Markus; Buchwald, Elke; Karg, Siegfried; Pösch, Peter; Greczmiel, Michael; Strohriegl, Peter; Rieβ, W.

doi:10.1016/0379-6779(95)03426-k

Cited by 59 publications

(26 citation statements)

References 17 publications

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“…To overcome these difficulties, a number of polymers with oxadiazole units as side groups [36,37] or as part of the polymer main chain have been prepared [36][37][38][39][40]. Oxadiazole groups are well-known building blocks in temperature-stable polymers with high glass transition temperatures [41].…”

Section: Light-emitting Diodes Based On Ppv and Oxadiazole Polymersmentioning

confidence: 99%

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Heterolayer light-emitting diodes based on poly-phenylene vinylene

Rieß

1997

Polym. Adv. Technol.

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In order to enhance the quantum efficiency of poly‐p‐phenylene vinylene (PPV) light‐emitting diodes (LEDs), we have fabricated metal/insulator/polymer (MIP) LEDs and heterolayer LEDs based on PPV and oxadiazole polymers. The current–voltage (I–V) characteristics and electroluminescence (EL) intensity of the MIP structures display a pronounced dependence of the insulator thickness and we detect an increase in the quantum efficiency of more than a factor of 30 at an AlOx layer thickness of 3–6 nm. The device characteristics are qualitatively understood within inorganic metal insulator semi‐conductor (MIS) theory and can be explained by a voltage‐dependent barrier for minority carrier injection in connection with a hole‐blocking barrier at the PPV/insulator interface. Our oxadiazole polymers used in the heterolayer polymeric devices are characterized by a high thermal stability and excellent film‐forming properties. These materials act as efficient hole‐blocking, electron transport and injection layers in PPV‐based LEDs and we measure a significantly improved device performance with external quantum efficiencies of more than 0.5%. Temperature‐dependent investigations point to a relatively balanced charge carrier injection and reveal the influence of space charge limited currents on the device performance at low temperature. © 1997 John Wiley & Sons, Ltd.

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Section: Light-emitting Diodes Based On Ppv and Oxadiazole Polymersmentioning

confidence: 99%

“…5. For details of the synthesis and the chemical and optical properties, see refs [36][37][38][39][40]. The low molar mass model compounds 2a-c were prepared in order to test the suitability of the novel oxadiazoles as ETLs in LEDs.…”

Section: Light-emitting Diodes Based On Ppv and Oxadiazole Polymersmentioning

confidence: 99%

Heterolayer light-emitting diodes based on poly-phenylene vinylene

Rieß

1997

Polym. Adv. Technol.

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“…15 and as emitting layers in electroluminescent devices. 16 respectively. Among the 1, 3, 4-oxadiazoles, pyrazole containing 2, 5-disubstituted-1, 3, 4-oxadiazoles are found to have considerable interest in medicinal chemistry because of their various biological characterized possessed by these compounds like antimicrobial, 17 antioxidant, 18 DNA photocleavage activity, 19 anticancer, 20 anti-inflammatory 21 and antiviral 22 activities.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of 2-phenyl-5- (1-phenyl-3-(3, 4, 5-trimethoxyphenyl)-1H-pyrazol- 4-yl) - 1, 3, 4-oxadiazole Scaffolds for Assessing Their Medicinal Potentials

Chennapragada¹,

Palagummi²

2018

IJPER

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Objective: The present research is aimed at the discovery and development of 1-phenyl-3-(3,4,5-trimethoxyphenyl)-1H-pyrazole derivatives as a series of novel 1, 3, 4-oxadiazoles (7a-7h) through iodine-catalyzed oxidative cyclization of the hydrazone derivatives (6a-6h) in the presence of potassium carbonate as base and DMSO as solvent in good toexcellent yields. Methods: The structures of all the newly synthesized compounds (6a-6h) and(7a-7h) were well characterized by IR, 1H NMR, 13C NMR and HRMS. Furthermore, allthe synthesized compounds (6a-6h and 7a-7h) were evaluated for their antimicrobial andanti-oxidant activities. Results: The research results revealed that the compound 6d (Z)-2-bromo-N'-((1-phenyl-3-(3, 4, 5-trimethoxyphenyl)-1H-pyrazol-4-yl) methylene) benzohydrazide) has antimicrobial potent while the synthesized compounds 6a (

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“…Oxadiazole derivatives have been widely used as electron transporting/hole blocking materials in LED devices and LED blends because oxadiazole unit has many excellent properties on the better chromophore, high thermal and oxidative stability, and the good charge injection and transporting building blocks. [21][22][23] In our paper, M-3, 1,3,4-oxadiazole-2,5-bis(4-vinylbenzene) is introduced into the chiral polymers main chain backbone to maintain conjugation between the oxadiazole and binaphthyl segments so that the electron transporting properties of the polymers may be improved. In addition, by introducing oxadiazole, an electron deficient moiety into the main chain, the electron density may shift away from the vinyl bond, which could increase the stability of the resulting chiral polymers.…”

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confidence: 99%

Synthesis and Characterization of Polybinaphthyls Incorporating Chiral (R) or (S)-2,2′-Binaphthyl Entities by Heck Reaction

Cheng

Chen

Song

et al. 2005

Polym J

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ABSTRACT:Four chiral conjugated polymer-1 (P-1), polymer-2 (P-2), polymer-3 (P-3) and polymer-4 (P-4) were obtained by the polymerization of (S)-6,60 -dibromo-2,2 0 -bisbutoxy-1,1 0 -binaphthyl ((S)-M-1) and (R)-6,6 0 -dibromo-2,2 0 -bisbutoxy-1,1 0 -binaphthyl ((R)-M-1) with 1,4-divinyl-2,5-dibutoxybenzene (M-2) and 1,3,4-oxadiazole-2,5- 1-4 (R) or (S)-1,1 0 -binaphthol (BINOL) have often been used as the starting materials for obtaining chiral binaphthyl compounds. The 2,2 0 -hydroxyl groups of BINOL can be easily converted into other functional groups and the 3,3 0 -and 6,6 0 -positions of binaphthyl skeletal structure of BINOL can be selectively functionalized at the well-defined molecular level, leading to a variety of binaphthyl derivatives which can exhibit remarkably stable chiral configuration as well as high chiral induction in molecular recognition, 5-9 asymmetric processes.10-15 These rigid and sterically chiral polybinaphthyl polymers also represent a new generation of materials for applications in chiral sensors, polarized light emission and nonlinear optical materials. [16][17][18][19][20] Conjugated polymers with rigid -systems often possess poor solubility, which seriously inhibits full structural elucidations and property investigations. We choose M-2 and M-3 as the conjugated molecular bridge linkers. Oxadiazole derivatives have been widely used as electron transporting/hole blocking materials in LED devices and LED blends because oxadiazole unit has many excellent properties on the better chromophore, high thermal and oxidative stability, and the good charge injection and transporting building blocks. [21][22][23] In our paper, M-3, 1,3,4-oxadiazole-2,5-bis(4-vinylbenzene) is introduced into the chiral polymers main chain backbone to maintain conjugation between the oxadiazole and binaphthyl segments so that the electron transporting properties of the polymers may be improved. In addition, by introducing oxadiazole, an electron deficient moiety into the main chain, the electron density may shift away from the vinyl bond, which could increase the stability of the resulting chiral polymers. 24,25 To make soluble conjugated polymers, the alkyl groups substitutents on the phenyl and binaphthyl rings as side chain of the polymers can improve solubility in organic solvents and facile electro-optical sensors. Heck, Suzuki, Stille and Sonogashira reactions are the most important C-C coupling reactions in organic chemistry synthesis. Herein, we present preliminary results of synthesis and properties of four polymers based on the chiral unit 1,1 0 -binaphthyl structure. The four chiral polymers containing vinylene linkages between naphthyl and phenyl groups can reduce steric hindrance between backbone rings and groups, and also have a beneficial effect on delocalizable -electronic conjugation structure of polymers. These polymers are green-blue light emitting materials with very good fluorescence quantum efficiencies. EXPERIMENTAL General1 H, 13 C NMR spectra measurements (all in CDCl 3 ) were recorded...

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Heterolayer light-emitting diodes based on new oxadiazole polymers

Cited by 59 publications

References 17 publications

Heterolayer light-emitting diodes based on poly-phenylene vinylene

Heterolayer light-emitting diodes based on poly-phenylene vinylene

Synthesis and Characterization of 2-phenyl-5- (1-phenyl-3-(3, 4, 5-trimethoxyphenyl)-1H-pyrazol- 4-yl) - 1, 3, 4-oxadiazole Scaffolds for Assessing Their Medicinal Potentials

Synthesis and Characterization of Polybinaphthyls Incorporating Chiral (R) or (S)-2,2′-Binaphthyl Entities by Heck Reaction

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