Temperature dependencies in organic photorefractive materials

Altering the sample temperature in a photorefractive material changes the rotational mobility of the chromophores. A change of three orders of magnitude in the response times over a temperature change of 12 K has been observed. In the photorefractive experiment, however, the chromophore orientation is induced by the non-instantaneous change of the space charge field. The finite speed of the latter causes the chromophore answer to be different from their normal relaxation behaviour to an instantaneous change. This effect is most pronounced when both time constants are in the same range.