Electric Field Effects on Photoconductivity and Electronic Absorption Spectra of Photogeneration Sites in Amorphous Molecular Semiconductors

Field dependences of photogeneration quantum yields of charge carriers in films of amorphous molecular semiconductors at high external electric field strengths cannot be always explained in terms of the Onsager or the Poole–Frenkel model, which do not consider the effect of an electric field on basic parameters of these materials. It is assumed that an external electric field shifts the electron density in molecules from its equilibrium distribution, thus altering the probability of electronic transitions. The assumption has been verified in studying the effect of an external electric field on the absorption spectra of poly(N-epoxypropylcarbazole) films doped with a merocyanine dye. Correlation between the theoretical and experimental results has been obtained.