Influence of molecular weight on the photorefractivity of polymer/liquid crystal composites

We report on photorefractive composites composed of poly(N-vinyl carbazole) (PVK)/liquid crystal/C60 with PVK of different molecular weight (MW). The influence of MW on the photorefractivity was studied. The results show that a higher MW leads to a larger two-beam coupling coefficient Γ and a larger effective electric–optical coefficient. Γ over 200 cm−1 is observed for the composite based on the highest MW PVK.