Structure-Properties Relationship of Phenylethenyl-Substituted Triphenylamines

Diversity of the (opto)electronic devices in which the derivatives of triphenylamine are used requires thorough knowledge of the structure-properties relationship of this class of organic semiconductors. Diphenylethenyl- or methylphenylethenyl-substituted triphenylamines were prepared by condensation of methoxy-substituted triphenylamines with 2,2-diphenylacetaldehyde or 2-phenylpropionaldehyde, respectively. Diphenylethenyl-substituted triphenylamines form molecular glasses with glass transition temperatures up to 50 degrees C. Increasing the number of phenylethenyl substituents resulted in suppression of intramolecular motions of the triphenylamine core, thereby significantly (up to 48%) enhancing fluorescence quantum yield of the derivatives in solutions. The enhancement was more pronounced for diphenylethenyl-substituted triphenylamines. The ionization potentials of the synthesized materials do not depend on the number and the structure of substituents and are ca. 5.3 eV. Hole drift mobility of the glassy layer of bis 4-(2,2-diphenylethenyl)phenyl](4-methoxyphenyl)amine reach 1.8 x 10(-2) cm(2)/V-s at an electric field of 1 x 10(6) V/cm.