TITLE:
Differentiation of the Aging Process of PEDOT:PSS Films under Inert Helium and Ambient Atmosphere for Two Different Rates of Thermal Treatment
AUTHORS:
Sotirios Sakkopoulos, Evangelos Vitoratos
KEYWORDS:
Conducting Polymers; PEDOT:PSS; Thermal Treatment; Organic Electronics
JOURNAL NAME:
Open Journal of Organic Polymer Materials,
Vol.4 No.1,
December
27,
2013
ABSTRACT:
The conductivity
difference Δσ between two similar PEDOT:PSS films, 120 nm thick, heated by 5 and 15 K/min from 80 to
440 K, the one under inert He and the
other under ambient air gives an approximate measure of the influence of oxygen
and moisture on the conductivity vs temperature T. The resulting curves Δσ = f(T) exhibit three different regions: at temperatures from 80 to 145 K
for heating rate 5 K/min and from 80 to 200 K for 15 K/min, an intense
degradation of the sample under ambient atmosphere was revealed by the abrupt
increase of the difference of the conductivities between He and atmospheric
air. At intermediate temperatures from 145 to 380 K for 5 K/min and 200 to 400
K for 15 K/min, the conductivity difference remains basically constant indicating a stabilization of the damage produced
by oxygen and moisture. Finally, for temperatures higher than 380 to 400 K the
degradation increases again. An explanation of this behavior is proposed based
on the hydrophilic character of the PSS and the destructive role of oxygen at
high temperatures. Moreover, the isotherms σ = σ(t), where t is the
heating time, at 443 K, under inert He and under atmospheric air for one hour
verify the significant
role of oxygen and moisture on the electrical conductivity. Under He the
conductivity increases monotonically
with t, but under ambient air factors the conductivity competes with others decreasing it producing a maximum
at about t = 10 min.