Unifying electrochemical and field-effect mechanisms in electrolyte-gated organic field-effect transistors
(English)Manuscript (preprint) (Other academic)
The combination of electrolytes and organic semiconductors has opened up new opportunities in photonics1, electronics2 and in energy storage3. In most of these devices, the key mechanisms involve the transport of charge carriers (electrons or ions) across the organic semiconductor-electrolyte interface. The formation of an electric double layer (EDL) at this polarized interface is fuzzier than at a metal-electrolyte interface since weak intermolecular interactions in the organic solid favour the penetration of ions4. An EDL established at the organic semiconductor-electrolyte interface, defined by a sheet of electronic charge carriers and a sheet of ions, has been proposed recently as the basic mechanism for electrolyte-gated organic field-effect transistors (EGOFETs)5, 6. Here, organic thin film transistors are used as a probe to investigate the organic semiconductor-electrolyte interface. We demonstrate that the capacitance value of the gate counter electrode dictates the degree of advancement7 of the electrochemical halfreaction (the extent of the reaction) at this interface. This finding unifies the mechanisms proposed for EGOFETs and organic electrochemical transistors (OECTs); and sets the ground description for an electrochemical half-reaction induced entirely by capacitive coupling.
IdentifiersURN: urn:nbn:se:liu:diva-67886OAI: oai:DiVA.org:liu-67886DiVA: diva2:414016