A New Carbazole-based Conjugated Multibranched Molecule and Its Tetramer as Hole Transporting Materials

Abstract

A conjugated multibranched molecule. 1.3,5-tris{(E)-2-[9-hexyl-9H-carbazol-3-yl]vinyl} benzene (THCEB) and its tetramer, 1,3,5-tris((E)-2-{9-[6-(3-{(E)-3,5-bis[(E)-2-(9-hexyl-9H-carbazol-3-yl)vinyl]styryl} -9H-carbazol-9-yl)hexyl]-9H-carba-zol-3-yl}vinyl)benzene (4(THCEB)), have been synthesized through Heck coupling and Horner-Emmons reactions in moderately good yields. These compounds exhibited good self-film-forming properties by spin coating. These two large molecules showed an absorption maxima at around 346-348 tun in their solution states. The maximum PL intensities of THCEB and 4(THCEB) films were commonly observed at around 450 nm, except for a strong emission band at 535 nm in THCEB.. In the tetramer, the emission at 535 nm was highly Suppressed. This observation was explained in terms of the time-resolved photophysical properties of these molecules with the help of a possible mechanism.