Using the nonsteady-state photo-EMF technique for verification of Einstein relation in PVK based photoconductive polymers

In this paper, we propose relatively simple experimental procedure for measuring the diffusion coefficient D and drift mobility in a single experimental configuration, which can be used for verification of the Einstein relation in amorphous photoconductors. Our method is based on utilisation of the nonsteady state photo-EMF effect excited in the bulk of a photoconductor by a vibrating light interference pattern. Experimental results obtained in a photoconductive polyvinylcarbazole-based polymer in reflectance configuration are presented. In our analysis we consider a monopolar photoconductor with arbitrary structure of trapping centres and no saturation of these centres during formation of the space charge field.