Full functional photorefractive molecule with large two-beam coupling gain

We have synthesized two Carbazole-based monolithic monomers, 3-[9-(2-Ethyl-hexyl)-9H-carbazol-3-yl]-2-(4-nitrophenyl)-acrylonitrile (M1) and (Z)-2-((9-(4-ethylhexyl)-9H-carbazol-6-yl)methylene)-4-oxopentanenitrile (M2), which contain both photoconductive and electro-optic chromophore. The melting point were measured to be 151 degrees C (M1) and 77 degrees C(M2) respectively, which are higher than the room temperature. No crystallization of their films is observed at room temperature. One of the monomers M1 exhibits good photorefractive performance. The two-beam coupling gain coefficient of M1 is measured to be 372 cm(-1) at 50 V/mu m, while the two-beam coupling gain coefficient of M2 is only 17 cm(-1) at 42 V/mu m. By applying ellipsometric technique, we deduced that the better PR performance of M1 was due that M1 has larger effective electro-optic coefficient. The photorefractive index modulation of M1 was measured to be 6 x 10(-3) at an electric field of 48.3 V/mu m. Further investigation on the structure-property relationship has also been demonstrated.