Observation of the transition from adiabatic to nonadiabatic small polaron hopping in a molecularly doped polymer

Abstract

The transition from adiabatic to nonadiabatic small polaron hopping has unique characteristics among hopping theories; an activation energy in the mobility that changes from being monotonically increasing with the mean distance between hopping sites, ρ, to being independent of ρ, and, simultaneously, an Arrhenius prefactor that changes from being independent of ρ to exponentially decreasing with ρ. We have observed such a transition for the first time in the hole mobilities of the molecularly doped polymer, tri-p-tolylamine:polycarbonate.