Highly efficient photorefractive composites based on layered photoconductive polymers

High-performance photorefractive materials based on the layered photoconductive polymers PPT-CZ [rigid backbone of poly(p-phenyleneterephthalate) with pendent carbazole groups] are studied. The composites are composed of PPT-CZ and are doped with the sensitizer C-60 and nonlinear optical chromophores. Despite the absence of a plasticizer and the lower concentration of the carbazole photoconductive moieties as compared with poly(N-vinyl carbazole), these materials show high photorefractive sensitivity, i.e., S-n2 of 70 +/- 7 cm(2)/kJ at E-0 = 100 V/mum for PPT-CZ(n = 12): diethylaminodicyanostyrene:C-60. The low glass transition temperature (<0degreesC) leads to a high rotational mobility of the chromophores that results in large refractive-index changes. For all the composites that were investigated, the two-wave mixing gain F exceeds 100 cm(-1) at an applied field of 50 V/mum. (C) 2003 Optical Society of America.