Oxygen-driven doping of conjugated polymers in aqueous media via anion adsorption

Solution-based chemical doping provides a simple and effective approach to controlling the carrier concentration of organic semiconductors through redox reactions. However, the role of molecular oxygen, which is the most abundant oxidant in air, has remained unclear. In this study, we demonstrate efficient oxygen-driven doping in aqueous solution by employing highly hydrophobic anions. Specifically, the use of tetrakis(pentafluorophenyl)borate (TFPB^-) as the dopant anion significantly enhances the doping efficiency and results in high electrical conductivity of up to 200 S cm^-1. This enhancement is attributed to increased anion activity at the solid-liquid interface. Quartz crystal microbalance measurements reveal that hydrophobic anions spontaneously aggregate in the aqueous phase and rapidly adsorb onto the organic semiconductor surface within 15 seconds. This work presents a simple and efficient strategy for oxygen-mediated doping. It also introduces a new design principle for controlling doping processes through interfacial molecular interactions.