In-Operando characterizatioN of anti-ambipolar mIxed Conductors

Objetivo

This proposal concerns the fundamental properties of mixed ion-electron conducting polymers. These materials are biocompatible and conduct both ions and electrons, making them excellent candidates for bioelectronic applications interfacing with living tissue. The conductivity of these materials increases under bias by injecting ions and concerted doping of the semiconducting polymer. However, upon high doping the conductivity can no longer increase but rather decrease. The exhibited maximum, where any voltage change lowers the conductivity, amounts to an anti-ambipolar response which finds applications in biorealistic artificial neurons. The underlying mechanisms, however, remain unknown in part because of the inherent instability of highly doped polymer semiconductors. Without understanding the fundamentals of these materials, targeted optimization and development are inhibited.
Additional complications arise from the complex environment in which they operate, consisting of ions and water. Their characteristics and response to doping are highly different in these conditions compared to ex-situ measurements, making in-operando characterization absolutely crucial. In-operando characterization is however not straightforward and requires specialized equipment.
In this IONIC proposal, a research plan is described to investigate the fundamentals underlying anti-ambipolarity by designing and building novel in-operando measurement tools, and applying them to a uniquely stable ladder-type polymer. This unprecedented approach allows for characterizing, for the first time, the doping interactions throughout the anti-ambipolar regime.
Project IONIC marks a major breakthrough in understanding organic semiconductor doping in electrolytes. The resulting general structure-property relations uncovered by the research described in this proposal will enable an intelligent design of material systems for exciting applications in bioelectronic interfacing and biomimicking circuitry.