Low-temperature electrical anisotropy of self-assembled organic films

Abstract

We have examined the low-temperature characteristics of the charge transport in self-assembled organic films with thickness varying from 5 to 60 deposited bilayers of polypyrrole and polythiophene acetic acid. When the temperature is progressively decreased, independent measurements of the longitudinal and transversal components of the resistivity tensor of these thin films reveal that while the conductivity along the surface directions has the expected semiconducting profile, the charge transport in the transversal direction exhibits a positive temperature coefficient ͑PTC͒. For the samples with a small number of deposited bilayers we observe that at very low temperatures the PTC characteristics disappear and a tunnelinglike current begins to dominate the transversal charge transport.

Electrical impedance spectroscopy investigation of surfactant–magnetite–polypyrrole particles

“…[37,44] for SDS-PPY-Fe 3 O 4 composites, by arguing that besides ionic transport several complementary processes are involved in the overall conduction mechanism through the solutions, such as charge mobility along the PPY chains and hopping through the metal oxide clusters present in the interior of the aggregates. As it is well known, whenever the density of polymeric chains in solution is large, charge transport processes associated with the hopping of the carriers along and between chains can become important [45]. In the inset we show the theoretical fitting to the experimental data of samples S1 and S8, using the parameters given in Table 4.…”

Electrochemical Synthesis and Characterization of Multi-walled Carbon Nanotubes/Polypyrrole and Polypyrrole Hollow Nanotubes

“…On the other side, the increase in the ion migration length in polymeric film (as a consequence of increasing thickness) represents an impediment in the development of polymeric structures with faster power energy storage. In order to circumvent these drawbacks, it has been reported the use of polypyrrole-coated carbon nanotubes that associates low mass density and large surface area (CNTs characteristics) (11) with elevated electrical conductivity, low toxicity and environmental stability (polypyrrole characteristics) (1,(12)(13)(14)(15)(16)(17).…”

Effect of the lithium cation on the sorption and electrical properties of amphiphilic block copolymers and their composites

“…On the other hand, the non‐Arrhenius behavior obtained in the conductivity of solid polymer ion electrolytes is the hallmark of ionic motion, being coupled with segmental motion of the host polymeric matrix. Thus, in this case, the conductivity depends on the temperature and is characterized by an apparent activation energy that changes with temperature 9, 11, 23…”