Synthesis and properties of photorefractive polyimine with carbazole unit

A new fully functionalized photorefractive polyimine was prepared by the condensation polymerization between a photoconducting carbazole derivative, 9-(2- ethylhexyl)carbazole-3,6-dicarbaldehyde, and a nonlinear optical stilbene chromophore, 4-[N,N-bis(2- aminoethyl)amino]-4'-nitrostilbene. It showed excellent solubility in common organic solvents such as chloroform, cyclohexanone, tetrahydrofuran, etc. and high optical quality films were obtained by free standing film casting. Very high second order optical nonlinearity with d33 equals 120 pm/V was observed by second harmonic generation at the fundamental 1064 nm wavelength. In demonstrated good thermal stability of the aligned dipoles by electric field up to ca. 125 degrees C. The diffraction grating was formed by the interference of two coherent Ar-ion laser beam at the wavelength of 488 nm. A holographic diffraction efficiency of about 15 percent has been achieve din a 10 micrometers -thick film. Storage state of our film shows remarkably long stability at room temperature.