Determination of the density of recombination centers in a photorefractive guest-host polymer

The density of deep traps for charge carriers significantly determines both the amplitude and the phase of the internal space-charge modulation in photorefractive polymers. We have measured the photoconductivity of a photorefractive guest-host polymer as a function of the external electric field and the sample temperature. Using theoretical models for charge carrier generation, transport and recombination, the density of recombination centers can be extracted. It is closely related to the density of deep traps. The results are compared with the density of pertinent traps, as obtained from phase shift measurements by holographic two-beam coupling techniques. (C) 1998 Elsevier Science S.A. All rights reserved.