Films of poly(3-alkylthiophenes) on glass substrates were oxidized wit
h acetonitrile solutions of AuCl3 to yield electronically conductive m
aterials containing the AuCl4- counterion, whereas oxidation with nitr
omethane solutions resulted in both AuCl4--doped polymer and electrole
ss deposition of metallic gold, X-ray photoelectron spectroscopy (XPS)
has been used to investigate the chemical nature of the counterion an
d the chemical evolution of interfaces during oxidation. XPS confirms
AuCl4- as being the sole gold species present in films oxidized in ace
tonitrile. XPS of films oxidized using nitromethane solutions indicate
that AuCl4- and Au(O) are present in the bulk and at the polymer/solu
tion and polymer/ substrate interfaces immediately following oxidative
doping. However, metallic gold continues to deposit at the polymer/so
lution interface well beyond the period required for complete oxidativ
e doping, The localization of metallic Au at this interface was confir
med by XPS and depth profile Auger electron spectroscopic analysis, Th
e electroless deposition process is autocatalytic in nature and leads
to the formation of a homogeneous metallic layer which increases the c
onductivity of the film to values in excess of 10 000 Omega(-1) cm(-1)
. The high conductivity is solely due to the presence of the metallic
layer, the underlying polymer film possessed a conductivity 15 Omega(-
1) cm(-1). The solvent dependency of the electroless deposition proces
s is due to the solvent's ability to coordinate with Au(I) intermediat
es, formed during oxidative doping, prior to disproportionation into A
u(O).