An axis-selective photosensitized reaction of a photo-cross-linkable liquid crystalline polymer film doped with a triplet photosensitizer (TPS) based on axis-selective triplet energy transfer achieved a thermally enhanced molecular reorientation of the film using linearly polarized (LP) 405 nm light. Four types of TPS4,4‘-(N,N ‘-bis(diethylamino))benzophenone (DBP), 4-(N-diethylamino)benzophenone (BP), 5-nitroacenaphthene (AN), and p-nitroaniline (pNA)were used to compare the efficiency of the axis selection of the energy transfer. In all cases, the photoreactivity of a film was generated when doping with less than 9 wt % of TPS. The quenching sphere played a role in the photoreactivity, while the photoinduced optical anisotropy depended on the type of TPS. The axis-selective photoexcitation of TPS and the polarization-preserved energy transfer to the photoreactive mesogenic groups dominated the photoinduced optical anisotropy as well as the thermal enhancement of the molecular reorientation.

Polarization-selective photosensitization and molecular reorientation in photo-crosslinkable polymer liquid crystal (PMCB6M) films, based on polarization-selective triplet energy transfer using LP-365 nm and LP-405 nm light with different photosensitizers, are described. A dramatic improvement in the photoreactivity of the film was observed with a small amount of photosensitizer; and a high degree of molecular reorientation and slantwise reorientation were generated when annealing the resulting films at elevated temperatures. The efficiency of reorientation depended on the photoinduced dichroism of the film.