Comparative study of hole transport in poly(<i>p</i>-phenylene vinylene) derivatives

TLDR

The study measures the dc hole mobility of four PPV derivatives across temperature and electric field, and relates the extracted microscopic transport parameters to polymer composition. Mobility data were fitted with a correlated Gaussian disorder model to determine energetic disorder, localization length, and transport-site separation. All polymers exhibit μ∝exp(γ√E) behavior, and for fully conjugated polymers the temperature and field dependence is fully governed by energetic disorder.

Abstract

The dc mobility of holes in four poly(p-phenylene vinylene) (PPV) derivatives (three fully conjugated polymers with different side chains and one partially conjugated PPV) is examined as a function of temperature T and applied electrical field E. In all cases the mobility $\ensuremath{\mu}$ follows the empirical $\ensuremath{\mu}\ensuremath{\propto}\mathrm{exp}\ensuremath{\gamma}\sqrt{E}$ law. The specific temperature and electrical field dependence of the mobility is fitted within a (correlated) Gaussian disorder model. From the fits the energetic disorder, localization length, and average transport-site separation are determined. In the case of the fully conjugated polymers the different T and E dependencies of $\ensuremath{\mu}$ are completely determined by the energetic disorder. The relation between the obtained microscopic transport parameters and the specific chemical composition of the polymer material is discussed.