DIPOLE RELAXATION DURING CHARGE-TRANSPORT IN POLYMERIC PHOTOCONDUCTORS

The photoinduced current measured without external electric field is caused not only by charge transit through the sample but also by relaxation of the molecular dipoles. This dipole relaxation changes the current direction. Measurements of the photocurrent were carried out after laser flash on poly(N-vinylcarbazole) with trinitrofluorene (PVK/TNF) and on polysiloxane with carbazole side groups (PS). The mobility of charge carriers, the coupling factor between dipole polarization and electric field and the relaxation time of molecular dipoles can be discussed by using a theoretical model of charge transit and dipole relaxation.