Understanding the Electrochemical N-Type Doping Process of Polyoxadiazole OMIEC Materials

As ion-electron dual conductors, organic mixed ionic electronic conductors (OMIECs) find wide-ranging applications in supercapacitors, batteries, and biosensors. However, the electrochemical doping of n-type OMIECs has been studied much less due to the scarcity of suitable n-type models for research. An n-type polyoxadiazole (POD) OMIEC with adjustable electronic and ionic conductivity is designed to help in understanding the doping process. Our systematic study focused on the influence of POD OMIEC’s conductivity, doping ions, and the conductivity of doping ions on the doping process. Our data reveal that the electrochemical doping process, involving electron injection into the POD and compensation by doping ions, is impacted by several factors: (1) The lower electronic conductivity compared to ionic conductivity presents a limitation in the POD doping process; (2) the desolvation process occurs when solvated doping ions enter the polymer from the electrolyte. The magnitude of the desolvation energy affects the degree of POD doping. (3) The high conductivity of doping ions in the electrolyte facilitates rapid migration to the polymer surface, promoting the POD doping reaction. Understanding the POD electrochemical doping process can provide valuable insights into preparing high-performance OMIEC devices.