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A Hole‐Transporting Material with Controllable Morphology Containing Binaphthyl and Triphenylamine Chromophores
Author(s) -
He Q.,
Lin H.,
Weng Y.,
Zhang B.,
Wang Z.,
Lei G.,
Wang L.,
Qiu Y.,
Bai F.
Publication year - 2006
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200500541
Subject(s) - triphenylamine , materials science , chromophore , morphology (biology) , nanotechnology , photochemistry , chemical engineering , optoelectronics , chemistry , biology , engineering , genetics
An organic compound with two triphenylamine moieties linked with binaphthyl at the 3,3′‐positions (2,2′‐dimethoxyl‐3,3′‐ di(phenyl‐4‐yl‐diphenyl‐amine)‐[1,1′]‐binaphthyl, TPA–BN–TPA) can be synthesized by Suzuki coupling. Amorphous and homogeneous films are obtained by either vacuum deposition or spin‐coating from solution in good solvents, while single crystals are grown in an appropriate polar solvent. X‐ray crystallography showed that a TPA–BN–TPA crystal is a multichannel structure containing solvent molecules in the channels. The intramolecular charge‐transfer state resulting from amino conjugation effects is observed by solvatochromic experiments. The high glass‐transition temperature (130 °C) and decomposition temperature (439 °C) of this material, in combination with its reversible oxidation property, make it a promising candidate as a hole‐transport material for light‐emitting diodes. With TPA–BN–TPA as the hole‐transporting layer in an indium tin oxide/TPA–BN–TPA/aluminum tris(8‐hydroxyquinoline)/Mg:Ag device, a brightness of about 10 100 cd m –2 at 15.6 V with a maximum efficiency of 3.85 cd A –1 is achieved, which is superior to a device with N , N′ ‐di(1‐naphthyl)‐ N , N′ ‐diphenyl‐[1,1′‐biphenyl]‐4,4′‐diamine as the hole‐transporting layer under the same conditions. Other devices with TPA–BN–TPA as the blue‐light‐emitting layer or host for a blue dye emitter are also studied.