All parameters describing the charge carrier dynamics in a poly͑phenylene vinylene͒-based photorefractive ͑PR͒ composite relevant to PR grating dynamics were determined using photoconductivity studies under various illumination conditions. In particular, the values of the coefficients for trap filling and recombination of charges with ionized sensitizer molecules could be extracted independently. It is concluded that the PR growth time without preillumination is mostly determined by the

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... ion between deep trap filling and recombination with ionized sensitizer molecules. Further, the pronounced increase in PR speed upon homogeneous preillumination ͑gating͒ as reported recently is quantitatively explained by deep trap filling.