Electrophysical properties of poly(N-vinylcarbazole)-carbon nanotubes composite films

The specific features of charge carrier transport in poly(N-vinylcarbazole) films doped with single-wall carbon nanotubes have been investigated. The mobilities of electrons and holes in ITO-polymer composite-Al samples have been determined by the time-of-flight method and by measuring the voltage-current characteristics of steady-state currents. According to the time-of-flight experiments, in the films of a poly(N-vinylcarbazole)-0.26 wt % single-wall carbon nanotubes composite, the drift mobility of electrons lies within (1.2–4.5) × 10^?6 cm²/(V s) and exceeds the mobility of holes by a factor of 5. The shape of the transient current suggests the dispersion character of transport of electrons and holes. With an increase in the concentration of single-wall nanotubes from 0.26 to 0.43 wt %, the conductivity of the composite films increases by two orders of magnitude; that is, the threshold of conductivity percolation has been achieved. A simple model is proposed to describe the transport of charge carriers in the polymer system under study.