Photoalignment effect in a liquid-crystal film doped with nanoparticles and azo-dye

This study discusses the photoalignment effect in a liquid-crystal (LC) film that is doped with nanoparticles and azo-dye. The vertical alignment induced by nanoparticles of polyhedral oligomeric silsesquioxanes can be changed into homogeneous alignment by the absorption of photoexcited azo-dye. An electrically tunable polarization-dependent LC phase grating is also produced using the method. Both nanoparticle- and azo-dye-induced vertical and homogeneous alignments are noncontact alignment and are highly promising for low-temperature plastic processes.