posted on 2013-07-31, 00:00authored byVanessa Armel, Jonathan Rivnay, George Malliaras, Bjorn Winther-Jensen
In-situ-polymerized
films of poly(3,4-ethylenedioxythiophene) (PEDOT) are
known to be relatively ordered materials and maintain this order under
changing chemical and electrochemical conditions. It is therefore
surprising that certain ionic liquids (ILs) were found to interact
with PEDOT and thereby to a large extent disrupt the ordered structure.
The current work demonstrates the expansion of the interlayer distance
(d100) of PEDOT and the composite of PEDOT
with poly(ethyleneglycol) (PEDOT(PTS):PEG) in the presence of
IL mixtures containing triisobutylmethylphosphonium
tosylate (P1444PTS) and water. In presence of the mixtures,
the PEDOT(PTS):PEG film expands up to ∼100% while the PEDOT(PTS)
film expanded ∼50%. The expansion did not increase the electrical
resistance but increased the absorption in the π–π*
range, which can be explained by increased shielding of the PEDOT
chains by the IL. The incorporation of P1444PTS increased
the capacitance by 350%, compared to the theoretical capacitance of
PEDOT(PTS), due to the formation of additional double-layer capacitance.