A Hole‐Transporting Material with Controllable Morphology Containing Binaphthyl and Triphenylamine Chromophores

Abstract

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.

Bis(carbazol-9-ylphenyl)aniline End-Capped Oligoarylenes as Solution-Processed Nondoped Emitters for Full-Emission Color Tuning Organic Light-Emitting Diodes

“…Both devices XII and XIII emit a bright green luminescence (λ em = 520 nm, CIE coordinates of (0.29, 0.53)) under applied voltage. The EL spectra match well with the PL spectrum of Alq 3 , the EL of the reference devices (XIV and XV), and other reported devices. , No emission at longer wavelengths indicating the formation of exciplex species at the interface is detected. From these results, and in view of the fact that a barrier for electron migration at the Alq 3 /HTL interface (≈0.9 eV) is higher than that for hole migration at the HTL/Alq 3 interface (≈0.6 eV) (Figure b), both BCPA and BCPA-F will act only as HTL, and Alq 3 will act preferably as an electron blocker more than as a hole blocker and charge recombination thus is confined to the Alq 3 layer.…”

Synthesis and photoluminescence properties of novel polyarylates bearing pendent naphthylamine chromophores

“…The maximum PL intensity of polyarylate film of Ib was observed at 448 nm, which is perfectly blue in color. However, the red-shifted PL spectrum of polyarylate film, compared to the fluorescence spectrum of the solution in THF, is probably due to the stronger interactions between repeating units of the polymer in the solid state [25]. This phenomenon was also previously reported in our laboratory [18].…”

Solution-Processable Red-Emission Organic Materials Containing Triphenylamine and Benzothiodiazole Units: Synthesis and Applications in Organic Light-Emitting Diodes

“…The UV absorption bands peaked at ca. 315−328 nm can be assigned to π−π* transitions . Also, the visible absorption peaks located around 490−500 nm resulted from an intramolecular charge transfer (ICT) from the donor (TPA) to the acceptor (BT) .…”