Msa. Abdou et S. Holdcroft, PHOTOCHEMISTRY OF ELECTRONICALLY CONDUCTING POLY(3-ALKYLTHIOPHENES) CONTAINING FECL4- COUNTERIONS, Chemistry of materials, 6(7), 1994, pp. 962-968
Irradiation of electronically conducting poly(3-alkylthiophenes) doped
with the FeCl4- counter ion results in a loss of electronic conductiv
ity (6 S/cm --> 10(-5) S/cm). The mechanism proceeds by (i) direct pho
tolysis of FeCl4- and (ii) photoreduction of FeCl4- to FeCl42- followe
d by (iii) electron transfer to bipolaronic residues. Upon prolonged p
hotolysis the products are neutral, nonconductive polymer and octahedr
al iron(III) complexes. Photochemical dedoping occurs in vacuo but is
greatly accelerated by moisture. The reaction is sufficiently facile t
o occur significantly under ambient light. Replacement of FeCl4- with
a less photolabile counterion, AuCl4-, results in a several orders of
magnitude increase in the longevity of the irradiated conducting polym
er. Photochemical mechanisms responsible for these observations are de
scribed.