Fast photorefractive polymer composites based on nanocrystalline J-aggregates of the cyanine dyes

Abstract

The hole and electron drift mobility, photoelectric properties as well as influence of temperature, dark current and also relative position of oxidation potentials of the interacting components on photorefractive characteristics of the composites from aromatic polyimide doped with nanocrystalline J-aggregates of a cyanine dye are presented. The nanocrystalline J-aggregates were used as the photosensitizers and also as nonlinear optical chromophores. The experimental electric field dependence of the charge carrier photogeneration efficiency is well fitted by Onsager equation when the quantum yield of the bound thermalized electron–hole pairs ϕ 0=1 and the initial separation of the charges in the pair r 0=14.1 Å. The charge photogeneration time constant determines the response time of the photorefractive grating formation. The polymer composites exhibit gain coefficient Γ=218 cm −1 and response time shorter than 20 ms at applied electric field 50 V/μm and a intensity of each writing beam 30 mW/cm 2. The net gain coefficient Γ− α=143 cm −1.