G. Zotti et S. Zecchin, DECAY OF ELECTROCHEMICALLY INJECTED POLARONS IN POLYTHIOPHENES - BIPOLARON STABILIZATION BY STRUCTURAL FACTORS, Synthetic metals, 87(2), 1997, pp. 115-118
In situ ESR measurements have shown that polarons generated in polybit
hiophene by electrochemical oxidation in acetonitrile decay to bipolar
ons. The decay follows a first-order kinetic law with half-life times
which increase as the oxidation level is increased. This phenomenon is
attributed to electrostatic crosslinking which makes the material pro
gressively stiff. Absence of polaron decay has been observed in alkoxy
- and alkyl-substituted polythiophenes and attributed to polaron stabi
lization in the solvent-swollen materials. The structural factors (pol
ymer matrix stiffening or swelling) are shown to be critical parameter
s in the long-debated stability of polarons in non-degenerate polyconj
ugated conducting polymers.