Energy-level structure and carrier transport in the poly(N-vinyl carbazole): trinitrofluorenone charge-transfer complex

Abstract

The photoinjection of electrons and holes from a sensitizing layer of amorphous selenium into films of the poly(N-vinyl carbazole) : trinitrofluorenone, PVK : TNF, charge-transfer complex has been studied by means of xerographic discharge techniques. The observed discharges are interpreted as being space-charge limited and thus allow a determination of the carrier mobilities as a function of TNF loading. The mobilities determined in this way are consistent with measurements reported which used the time-of-flight technique. The asymmetries of discharge observed depending on whether electrons or holes are injected from the selenium are thus associated with mobility limitations and not to significant energy barriers between the transport states in amorphous selenium and PVK : TNF. An upper limit can therefore be inferred for the separation between the transport states for electrons and holes in this charge-transfer complex.