A novel polyaryl ether based photorefractive composite

We report the synthesis of a novel charge-transporting polymer based on the charge-transport unit N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-bipheny l]-4,4'-diamine (TPD). Introducing approximately 30 wt % of the liquid elec tro-optic molecule 4-(N,N-diethylamino)-2-fluoro-(Z)-beta-methyl-(E)-beta-n itrostyrene (FDEAMNST) and small amounts of C-60 makes this polymer photore fractive. A full photorefractive characterization is presented. In this com posite a rather large electro-optic effect is observed due to the efficient plasticization by the electro-optic molecules of the host polymer. The dif fraction 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 ve ry low trap density, which is in agreement with a 90 degrees phase-shift be tween the illumination pattern and the refractive index grating. To increas e the trap density, molecules with a low ionization energy were dispersed i n the composite.