Dissipative charge transport in organic mixed ionic-electronic conductors.

The thesis project inserts itself in the field of material physics and organic electronics and aims to the formulation of a model that describes dissipative charge transport in organic mixed ionic-electronic conductors (OMIEC) immersed in a ionically conductive medium. Such materials combine biocompatibility with both electronic and ionic conductivity resulting to be promisingly suitable for bioelectronics applications. In this work I elaborate on the analogy between dissipative charge transport in neurons’ axons and in OMIEC to come out with a transmission line theory based model that describes the impact of intrinsic material transport parameters on the dissipation of electronic signals. The model is confirmed with experimental transport measurements in microstructured OMIEC devices. Impedance spectroscopy, phase sensitive potential analysis and atomic force microscopy are used to directly measure signal dissipation along OMIEC transport channel varying channel length and doping level. Our findings deliver the dispersion relation for electronic transport in mixed conductors immersed in conductive electrolyte. To quantify dissipation in such systems we introduce the propagation constant γ as a new figure of merit for the design of OMIEC-based devices working alongside the universally recognized figure of merit µC*. In this way, we can properly account for the importance of dissipation to guide materials design and to demonstrate the feasibility of OMIEC materials for specific applications