Hole transport through chromophores in a photorefractive polymer compositebased on poly(N-vinylcarbazole)

The hole mobility, as measured by the linear time-of-flight technique, is h igher than expected at (2 +/- 0.5) x 10(-6) cm(2) (V s)(-1) at an applied f ield of 50 V mu m(-1) in a photorefractive polymer composite. The component s were poly(N-vinylcarbazole), the electro-optic chromophore 1-(2'-ethylhex yloxy)-2,5,dimethyl-4-(4" nitrophenylazo)benzene together with sensitisor 2 ,4,7-trinitro-9-fluorenone. This mobility is unchanged within experimental accuracy after the replacement of the poly(N-vinylcarbazole) by the dielect ric polycarbonate. Polycarbonate in pure form without the chromophores is a n insulator. We conclude that hole transport in the photorefractive composi te occurs through the network of chromophores and not through the charge-tr ansport polymer. (C) 2000 Elsevier Science B.V. All rights reserved.