“The rectification mechanism in polyelectrolyte gel diodes”
Ionic driven devices have been increasingly investigated in the drive to develop flexible and biointegrable electronics. One such device is a polyelectrolyte gel diode capable of rectifying ionic current. However, the underlying mechanism behind the rectification of current in polyelectrolyte gel diodes is not fully understood. Based on experimental data, it has been proposed that the rectification is due to the asymmetric distribution of ions at the interface between two gels doped with a cationic polyelectrolyte on one side and an anionic polyelectrolyte on the other. Additionally, an electrochemical model has been proposed to explain the mechanism quantitatively. Here, we explore the mechanism proposed by the Yamamoto–Doi model and validate it by using experimental data. We show that the diode operates via a physical mechanism that involves the electrochemical generation of proton and hydroxyl ions at the electrodes to generate current. Exponential currents (J) in the forward bias were observed and J = A √-V with A inversely proportional to the gel ionization and V the potential) in the backward bias, which coincides with predictions of the electrochemical Yamamoto–Doi model. Additionally, we also confirm the dependence of the electrochemical model on the dopant concentration in the backward bias regime.