A Novel Polyaryl Ether Based Photorefractive Composite

We report the synthesis of a novel charge-transporting polymer based on the chargetransport unit N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine (TPD). Introducing approximately 30 wt % of the liquid electro-optic molecule 4-(N,N-diethylamino)2-fluoro-(Z)-â-methyl-(E)-â-nitrostyrene (FDEAMNST) and small amounts of C60 makes this polymer photorefractive. A full photorefractive characterization is presented. In this composite a rather large electro-optic effect is observed due to the efficient plasticization by the electro-optic molecules of the host polymer. The diffraction efficiency and gain coefficient (3.4% and 50 cm-1, respectively) are rather low. This is attributed to a low space-charge field due to a very low trap density, which is in agreement with a 90° phase-shift between the illumination pattern and the refractive index grating. To increase the trap density, molecules with a low ionization energy were dispersed in the composite.