Photodynamic properties of azobenzene molecular films with triphenylamines

Abstract

A new type of photochromic molecule containing three azobenzene groups, tris[(4-(phenylazo)diphenylamine) phenylamine] (TPPA), was synthesized and its photoinduced behavior was examined. Good optical quality TPPA films could be prepared by spin-coating. The photoinduced behavior of the TPPA films, such as photoinduced birefringence and surface relief grating (SRG) formation, was investigated. Compared to an azobenzene-functionalized polymeric PDO3 film, the TPPA molecular film showed a rapid response for photoinduced birefringence and SRG formation, but the saturated value for the birefringence was much smaller than that of the PDO3 azopolymer film. The dynamic behavior of SRG photofabrication was compared for two TPPA films with different morphologies: an amorphous film prepared by spin coating and a semicrystalline film prepared by vacuum thermal deposition. The crystallinity associated with the TPPA film strongly hampered photoinduced mass transport in the fabrication of SRG.