The d.c. conductivity sigma(dc) and the a.c. electric response of poly(3-decylpyrrole) prepared with different dopants and synthesis conditions were studied over a broad temperature (75-300 K) and frequency (100 Hz-40 MHz) range, both in bulk state (films) and in solution. Concerning films, the temperature dependence Of sigma(dc) followed Mott's law, with the hopping parameters strongly doping dependent. A.c. conductivity sigma(ac) was strictly coupled to d.c. transport, so that a master curve resulted from a plot of normalised complex permittivity versus a critical frequency proportional to sigma(dc). Similar results to the bulk case were observed for non-dilute solutions, whereas for very dilute solutions sigma(dc) scaled with temperature as the reciprocal of solvent viscosity. Moreover, a steeper bilogarithmic slope Of sigma(ac) versus frequency was found. Inter-chain charge transport in dilute solutions can be attributed to dissociated counterions diffusing through the solvent, whereas intra-chain hopping can eventually contribute only at high frequencies.
Inter-chain and intra-chain hopping transport in conducting polymers
CAPACCIOLI, SIMONE;
2004-01-01
Abstract
The d.c. conductivity sigma(dc) and the a.c. electric response of poly(3-decylpyrrole) prepared with different dopants and synthesis conditions were studied over a broad temperature (75-300 K) and frequency (100 Hz-40 MHz) range, both in bulk state (films) and in solution. Concerning films, the temperature dependence Of sigma(dc) followed Mott's law, with the hopping parameters strongly doping dependent. A.c. conductivity sigma(ac) was strictly coupled to d.c. transport, so that a master curve resulted from a plot of normalised complex permittivity versus a critical frequency proportional to sigma(dc). Similar results to the bulk case were observed for non-dilute solutions, whereas for very dilute solutions sigma(dc) scaled with temperature as the reciprocal of solvent viscosity. Moreover, a steeper bilogarithmic slope Of sigma(ac) versus frequency was found. Inter-chain charge transport in dilute solutions can be attributed to dissociated counterions diffusing through the solvent, whereas intra-chain hopping can eventually contribute only at high frequencies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
