Effects of aggregation of squaryl dye on photogeneration of charges in amorphous molecular semiconductors based on poly-N-epoxypropyl carbazole

Peculiarities of photoconductivity, photoabsorption, and photoluminescence of poly-N-epoxypropyl carbazole films doped with an intraionic dye are investigated. The anomalous temperature dependences of the photoconductivity of the films in the dye absorption region are explained by studying the effect of the dye concentration, temperature, and external electric field on the liberation of captured charges from the traps formed in the films as a result of doping. It is concluded that an increase in the dye concentration enhances its aggregation, intensifies the photogeneration of triplet electron-hole pairs, and narrows the spatial distribution of traps for holes in the vicinity of the dye. The hole charges captured in such traps are connected through the Coulomb interaction with negatively charged fragments of dye molecules. The traps are destroyed through thermal activation.