Study of photoisomerization and photo-orientation of cyano-substituted 4′-N,N-dimethylamino-nitrosilbene and phenylhydrazone derivatives doped films

Photo-induced trans-cis isomerization and orientation of cyano-substituted 4′-N,N-dimethylamino-nitrosilbene (DANS) and phenylhydrazone derivatives doped polymer films have been studied. Comparing with DANS, these molecules show large photo-induced optical anisotropy (POA) due to the addition of cyano-group onto CC or CN bond which makes these molecules be much more easily photoisomerized. The mechanism of POA can be understood well by the current theories. Qualitative and quantitative explanations were given based on the trans-cis quantum yield, absorption spectrum, cis-trans relaxation, interaction with the host polymer, and the molecular structure.