Mean mobilities of charge carriers in disordered media

Time-of-flight transient photocurrents in molecularly doped polymers are analyzed in terms of an effective velocity distribution, which is found to be normal. Combining this with a fractional power law to describe the current that would flow in a semi-infinite sample provides an accurate description of experimental data on many materials and allows the determination of mobilities with a precision significantly enhanced over previous graphical analysis. The mobilities are found to deviate systematically from the lnμ∼ E dependence previously suggested in the literature. © 1992 The American Physical Society.