| Abstract
| - We have studied the influence of electric field on fluorescence in particles of photoconductive TiOPc (I),TiOPc (IV), HOGaPc, and x-H2Pc dispersed in a polymer matrix. Electric field induced quenching of boththe integrated and time-resolved fluorescence were measured. Time-resolved fluorescence decays were analyzedby fitting the data to a sum of two exponentials, representing the fast and slow fluorescence components. ForHOGaPc, TiOPc(I), and TiOPc (IV), the fast fluorescence component exhibits both amplitude and lifetimequenching. These results indicate that carrier generation in HOGaPc, TiOPc(I), and TiOPc (IV) originatesfrom both relaxed and nonrelaxed intrinsic excited singlet states, while the trapped excitons do not lead tosignificant carrier production. In contrast, for x-H2Pc, significant amplitude quenching of the fast componentis observed only at high field, and the trapped excitons are an important source of photogenerated carriers.This indicates that x-H2Pc possesses at least some bulk-sensitized photocarrier generation. All of thephthalocyanines studied exhibited a quadratic dependence of integrated fluorescence quenching on electricfield, indicating the existence of a neutral carrier precursor state.
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