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

Artikel i vetenskaplig tidskrift, 2004

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 φ0=1 and the initial separation of the charges in the pair r0=14.1Å. The charge photogeneration time constant determines the response time of the photorefractive grating formation. The polymer composites exhibit gain coefficient Γ=218cm-1 and response time shorter than 20ms at applied electric field 50V/μm and a intensity of each writing beam 30mW/cm2. The net gain coefficient Γ-α=143cm -1.