Phenylquinoxaline Polymers and Low Molar Mass Glasses as Electron-Transport Materials in Organic Light-Emitting Diodes

Abstract

We present a new synthetic approach to both phenylquinoxaline polymers and low molar mass glasses. A palladium-catalyzed coupling of arylalkynes and bromobenzenes and subsequent oxidation of the triple bonds lead to the corresponding benziles. Reaction with diaminobenzidine yields poly(phenylquinoxalines) (PPQs), whereas the reaction with 1,2-diaminobenzenes leads to low molar mass bis(phenylquinoxalines) (BPQs) and tris(phenylquinoxalines) (TPQs). Both PPQs and TPQs carry tert-butyl or CF3− substituents and are fully soluble in chlorinated hydrocarbons. The starburst TPQs are able to form stable, low molar mass glasses. Cyclic voltammetry reveals that the TPQs have low-lying lowest unoccupied molecular orbitals levels at about −3.6 eV and are attractive as electron-transport materials in organic light-emitting diodes (LEDs). Two-layer LEDs with poly(phenylenevinylene) were fabricated that show a maximum brightness of 450 cd/m2.

Charge-Transporting Molecular Glasses

“…[23] Due to the high morphological stability of the spiro-linked compounds the devices still operate at temperatures well above 100 C. Some of the hole-transporting compounds shown above (for instance compounds 4a±e) and many other star-shaped compounds have also been successfully used in multilayer OLEDs. [7] Electron-transporting molecular glasses such as (Alq 3 ), oxadiazoles, [98,130] and phenylquinoxalines [100] enable the balancing of charge transport in OLEDs and thus improve their characteristics.…”

Synthesis of Thermally Cross-Linkable Fluorine-containing Poly(aryl ether ketone)s I. Phenylethynyl Terminated Poly(aryl ether ketone)s

“…16 1-Bromo-4-acetoxybenzene (BAB) was synthesized from 4-bromophenol according to the previous procedure. 16,17 8.0 g of BAB (37 mmol), 0.49 g of triphenylphosphine (1.9 mmol) and 14 mL of DMAc were placed in a 200 mL three-neck flask equipped with a condenser, a thermometer, an additional funnel and a nitrogen inlet tube. This solution was treated by freezethaw cycles to remove traces of dissolved oxygen.…”

Fluorescent solvatochromism of bi-polar ,-diphenylaminoaryl-substituted hexaazatriphenylenes, tetraazaphenanthrene, and quinoxalines

“…1,4,5,8,9,12-Hexaazatriphenylene (HAT) [2] and 1,4,5,8-tetraazaphenanthrene (TAP) having three and two electron-withdrawing pyrazine rings, respectively, are of interest as an electron-poor core structure of electron-transporting and hole-blocking functions [3]. Introduction of aromatic rings at the peripheral region of HAT and TAP makes the compounds emissive.…”