Effect of molecular weight of poly( N -vinyl carbazole)on photorefractive performances

We present here the effect of molecular weight of poly( N -vinyl carbazole) (PVCz) on photorefractive performances. Photorefractive composites with higher molecular weight of PVCz led to higher diffraction efficiency and faster speed of grating buildup. The fastest response time of 18 ms (grating buildup speed of 55.6 s − 1 ) was obtained at 45 V μ m − 1 . Higher diffraction efficiency and faster buildup speed of photorefractive composite with higher molecular weight of PVCz was ascribed to the larger Pockels effect due to larger number density of traps. Dimer cation sites preferentially formed along the longer molecular chain in higher molecular weight of PVCz seem to work as effective traps for hole carriers.