Abstract
Applying the intuitive multiple trapping theory, we have calculated the time-of-flight (TOF) charge-collection µτ product, (µτ)cc, under the condition of dispersive transport and find that (µτ)cc=(1/α-α)µ0τfd≈µ0τfd, where α is a temperature-dependent constant, µ0 is the free-carrier mobility, and τ fd is the TOF charge-collection free-carrier deep-trapping time. The steady-state photoconductivity µτ product, (µτ)ss, is argued to be (µτ)ss=µ0τfr where τfr is the steady-state free-carrier recombination lifetime. As a result, (µτ)ss/(µτ)cc≈τfr/τfd. Our calculation shows that the presence of dispersive transport does not affect the ratio of (µτ)ss and (µτ)cc, and that the difference between (µτ)ss and (µτ)cc is due almost entirely to a difference between the free-carrier recombination lifetime in the steady state and the free-carrier deep-trapping time in the TOF charge-collection experiment. The origin of the difference between (µτ)ss and (µτ)cc is discussed.