μSR Study of Charge Carrier Diffusion in Regioregular Poly(3-Butylthiophene-2,5-Diyl)

Temperature-dependent of charge carrier diffusion in regioregular-poly(3-butylthiophene-2,5-diyl) (RR-P3BT) has been studied by Longitudinal Field (LF) muon-spin-relaxation (μSR) method for determining intrachain and interchain charge carrier hopping mechanisms. It is found that the depolarization rates at the low temperatures below 50 K indicate that the H–0.5 field-dependent characteristics of the charge transport is dominated by mobility along the polymer chain (intrachain diffusion). With an increase in temperature, the charge carriers move perpendicular to the polymer chain (interchain diffusion), as characterized by the field dependence of depolarization rates of C-H0.5 curve. The initial change in the carrier mobility appeared at around 50 K to 75 K.