Controlling the dimensionality of charge transport in an organic electrochemical transistor by capacitive coupling
Within the EU integrated project ONE-P, the group of Professors Magnus Berggren and Xavier Crispin from Linköping University (Sweden), demonstrate that the capacitance value of counter electrode dictates the degree of advancement of the electrochemical half-reaction, i.e. the extent of the reaction.
The combination of electrolytes and electroactive materials, especially conjugated polymers, has opened up new opportunities for electrochemical devices. Their reversible operation traditionally involves the oxidation [or reduction] of the electroactive organic material at the working electrode and a second electrochemical half-reaction at a counter electrode.
The group of Professors Magnus Berggren and Xavier Crispin investigated that effect in a set-up equivalent to an electrochemical transistor and show that with a nanoporous counter electrode the entire electroactive polymer film is oxidized without the need of a second half-reaction at counter electrode, thus leading to a three-dimensional charge transport in the transistor channel. In contrast, a flat counter electrode localizes the electrochemical reaction right at the organic semiconductor-electrolyte interface, thus creating a confined electric double layer defined by a two-dimensional sheet of electronic charge carriers in the semiconductor and a sheet of ions in the electrolyte. Such electric double layer has fundamental implications for low-voltage organic electronics.
Those findings are reported online on September 27, 2011 in Advanced Materials
