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Abstract: Four novel blue luminescent hole transporting materials with N,N′-di(p-tolyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine as the core, containing triphenylamine units and olefinic linkers were synthesized and characterized by FT-IR, 1H NMR and HRMS. Their optical, electrochemical and thermal properties were investigated. Quantum-chemical calculations were performed to obtain their optimized structures and the electron distribution of the molecular orbital energy levels, and the experimental findings suggest that monosubstituted compounds have a similar energy gap to the bisubstituted compounds. The UV–Vis and photoluminescence spectra indicate that these compounds are blue luminescent materials. Cyclic voltammetry measurements show that the four compounds embody suitable highest occupied molecular orbital levels (in a range of −5.08 ∼ −5.14 eV) for hole injection. All of the compounds have excellent thermal stability, with decomposition temperatures above 400 °C and glass transition temperatures above 100 °C, which is of benefit to form stable amorphous glassy states. [Copyright &y& Elsevier]

Abstract: Two new blue luminescent hole transporting materials (HTM) containing triphenylamine, carbazole units and olefinic linkers (TM1 and TM2) were synthesized via Wittig reaction and characterized by 1H NMR, FT-IR, and HRMS. The compounds show good solubility in common organic solvents such as dichloromethane, chloroform, tetrahydrofuran and dimethyl formamide. Their optical, electrochemical and crystalline properties were investigated by using UV–Vis, photoluminescence (PL) spectra, cyclic voltammetry (CV) and differential scanning calorimetry (DSC), respectively. Quantum-chemical calculation was performed to obtain their optimized structures and the electron distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels. The UV–Vis absorption and PL spectra of the two compounds in solid state were found to be similar to that when they were in dilute THF, which suggests that these compounds remain as an amorphous state in solid films. CV measurements show that the two compounds embody suitable HOMO levels (in a range of −5.28 to −5.23eV) for hole injection, which is consistent with the calculation consequence. Two compounds possess high glass-transition temperature (Tg ) at 96.61 and 90.74°C for TM1 and TM2, respectively, suggesting the two compounds could form stable amorphous glassy states. The experimental results show that the synthesized compounds have great potential for application in organic light-emitting devices (OLEDs). [Copyright &y& Elsevier]

Film-forming property of organic semiconductors is one of crucial factors for the performance of flexible organic light-emitting diode. In this work, two hole transporting materials based on triphenylamine were synthesized, which showed an outstanding film-forming property and could form free-standing films with a diameter of 4 mm. The spin-coated films on the flexible substrates showed an unobvious mechanical failure bended with radius of curvature no less than 6 mm. Photoelectron yield spectroscopy show that the two compounds embody suitable highest occupied molecular orbital levels (−5.14 eV and −5.25 eV) for hole injection. The sandwiched organic light-emitting diodes use poly[2-(4-3′,7′-dimethyloctyloxy)-phenyl]- p -phenylenevinylene) as emitting and electron transporting layer showed higher stability with increasing operation current density, an maximum luminance level of 103,690 cd m −2 . It demonstrate that the as-synthesized hole transporting materials hold a promising in high brightness flexible organic light-emitting diodes. [ABSTRACT FROM AUTHOR]