Synthesises And Properties Of V-and Y-Shaped Electroluminence Materials Based On Triphenylamine Derivatives

The bule emitting materials for electroluminescent device needed in OLED haven't been resovled. The compounds based on triphenylamine not only have special photoelectric properties, but also have intense absorption in Uv-vis region indicating that they are suitable for bule electroluminescent materials.Ten linear-, V- and Y-shaped compounds based on triphenylamine with different substituents are designed and synthesized by Sandmeyer reaction;Ullmann reaction, Witting reaction, Vilsmeierreaction, and their structure are confirmed by MS, IR and ~1H-NMR. Their Photo-electricities are determined by UV-vis spectra, photoluminescent spectra, Cyclic Voltammetry. The electrochemistry behavior is analyzed;the influence of substituents on the properties of photo-electricity is systematically discussed.The wavelength of emission is red-shifted, while the absorption is blue-shifted with increasing solvents polarity. The absorption is ranged from 378 to 422 nm. The compounds with cyano-group exhibit intense yellow-green photoluminescence;other compounds exhibit intense blue photoluminescence. The fluorescence quantum efficiency and fluorescence intensity of the Y-shaped compounds are lower than V-shaped compounds. The exciting energy is 3.44 eV, indicating that low potential can drive these compounds to emitting light.The compounds based on triphenylamine have good hole-transporting property because they are easily ionized forming anion under electric field acting. The compounds with electron donor have two reversible redox processes in the cyclic voltammogram;while the compounds with electron acceptor only have one reversible redox process.The result indicates that HOMO level of compound is raised by electron-donating group (-N(CH3)2,-OCH3), the oxidative onset potentials, the band gap and the ionization potentials are decreased, while LUMO level is lowered by the electron-withdrawing group(-CN), the oxidative onset potentials and electron affinities are increased.Their band gaps (Eg), electron affinity (E_A) and ionization potentials (P_I) calculated are 2.51-2.82 eV, 2.69-3.62 eV and 5.41-5.82 eV, respectively, indicating that compounds are good candidates as electroluminescent materials with good hole-transporting property.