TRANSPORT OF CHARGE-CARRIERS IN POLYMERS WITH CONJUGATED DOUBLE-BONDSAND CHROMOPHORE SUBSTITUENTS

Direct time-of-flight measurements were used to study the effects of t emperature, electric field strength, and polarity of the medium on the transport of charge carriers in poly(N-(2-propynyl)carbazole) (PPC) a nd poly(N-(2-propynyl)phenothiazine) (PPP). In these compounds, the fo rmation of narrow bands is possible due to conjugated double bonds in the main chain, and the transport of charge carriers proceeds via the band mechanism with the repeated trapping of carriers on the traps. At the same time, the carbazolyl and phenothiazine side-chain groups, wh ich are not conjugated with the main chain, can act as localized trans port centers to realize the polaron mechanism of charge transfer. The mobility of charge carriers and the charge transfer activation energy prove to be independent of the polarity of the medium, which is explai ned by the transition from the polaron transport to the band transfer with multiple trapping. PPP is found to be one of the few polymers in which both holes and electrons are mobile.