Charge carrier trapping in poly(N-vinylcarbazole)-trinitrofluorenone films

An investigation of hole and electron photo-injection in films of the poly(N-vinylcarbazole)-trinitrofluorenone charge transfer complex by the time-of-flight technique revealed the presence of deep carrier traps. The hole trap density was estimated to be (6–13) × 10¹⁹m^-3 in films where poly(N-vinylcarbazole) is mixed with trinitrofluorenone in a 1:0.2 mole ratio with respect to the monomer unit. In 1:1 mole ratio films, the electron trap density was estimated to be (10–29) × 10¹⁹m^-3. In the film samples typically investigated the number of carriers injected per sample normally exceeded the number of deep traps in the sample. The fraction of injected charge that became trapped was small under these circumstances, and the majority of charge carriers were transported through the film.