Charge carrier trapping in the photorefractive polymer

摘要

The charge carrier trapping property of a guest-host system was investigated. The molecularly doped polymer (MDP) consisted of poly(N-vinyl carbazole), plasticizers, a nonlinear optical material, and a trapping molecule. The trapping molecules used were a carbazole dimer and a well-known charge transporting material, 4-(diethylamino)benzaldehyde diphenylhydrazone (DEH). The response time of a MDP doped with the carbazole dimer was faster than that of the MDP doped with DEH, whereas their lifetimes were almost the same. Semi-empirical molecular orbital calculations were carried out for these two trapping molecules and show that the carbazole dimer suffered a larger change in the molecular geometry when it was ionized. A longer lifetime and faster response time are expected by optimizing changes in molecular geometry.