Real-time analysis of mixed ion and electron transfer in a conjugated polymer during the doping and de-doping

Conjugated polymers have promising applications in electronics and energy storage due to the polymer’s tunable conductivity and redox activity. For example, the conductivity of poly(3-hexylthiophene) (P3HT) is heavily dependent upon the doping level and the dopant type. This feature becomes especially important when considering P3HT or similar conjugated polymers for devices that require switching between electronic states (conductive vs insulating). In this talk, the mechanism of mixed ion-electron transfer studied using electrochemical quartz crystal microbalance with dissipation monitoring is discussed. During cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) experiments, the mass change of the P3HT electrode is monitored in real-time. This leads to an understanding of how the doping level and ion transfer behavior change with current and voltage. Specific doping levels were then correlated with the conductivity of the polymer using in-situ conductance experiments. This effort gives valuable insight into the nature of mixed ion-electron transfer during the doping-de-doping process.