Static and Ultrafast Transient Photophysics of Mono- and Dual-Branched Triarylamines

Mono- and dual-branched molecules, {4-[2-(4-benzothiazol-2-yl-phenyl)-vinyl]-phenyl}-(4-methoxy-phenyl)-phenyl-amine (BS1) and bis-{4-[2- (4-benzothiazol-2-yl-phenyl)-vinyl]-phenyl}-(4-methoxy-phenyl)-phenyl-amine (BS2), are investigated with one- and two-photon static spectroscopy, and the femtosecond fluorescence up-conversion technique. The molecules show branch-based fluorescence emission at low quantum yield. Ultrafast non-radiative decay on a picosecond time scale is found and is attributed to intramolecular charge-transfer bridged by the central triphenylamine. The two-photon absorption cross-sections of BS1 and BS2 are 19.1 and 19.4 GM, respectively.