Light-emitting dyes derived from bifunctional chromophores of diarylamine and oxadiazole: Synthesis, crystal structure, photophysics and electroluminescence

The synthesis, structural, photophysical, electrochemical and electroluminescent properties of a novel class of bifunctional molecule are reported in which the hole-transporting triarylamine and electron-transporting oxadiazole components were combined. The strongly luminescent compounds displayed good thermal and morphological stability as well as intense fluorescence both in solution and thin film at room temperature. The effects of the introduction of substituents with different electronic properties upon their absorption and emissive characteristics were correlated with theoretical calculations using density functional theory computations. The photophysics and electrochemistry of such systems were compared to those for the corresponding molecule without an oxadiazole ring. The bipolar compounds could be vacuum-sublimed and applied as emissive dopants for the fabrication of electrofluorescent, organic light-emitting devices with relatively simpler device structures, which can emit tunable colors by varying the aryl ring substituents.