Effects of conductivity-enhancement reagents on self-healing properties of PEDOT:PSS films

Conducting polymers (CPs), poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films, have shown excellent applications in the field of flexible electronics. In most cases, conductivity-enhancement reagents, such as popular dimethyl sulfoxide (DMSO), ethylene glycol (EG) and polyethylene glycol (PEG) have been demonstrated as necessary additives. However, their effects on the self-healing performances of such films were still unknown. Here, effects of these reagents as well as inorganic concentrated sulfuric acid (H2SO4) on the water-induced mechanical and electronic (conductive and thermoelectric) self-healing properties of PEDOT:PSS films were studied and corresponding mechanisms were illustrated. Meanwhile, analogous poly(3,4-ethylenedioxyselenophene):poly(styrene sulfonate) (PEDOS:PSS) film was investigated as a contrast. Treatment by EG showed 98 % recovery of conductivity and significantly reduced crack width after healing, while H2SO4 post-treatment only improved the self-healing of mechanical properties but significantly weakened the electrical properties. PEG or DMSO treatment showed negative influence on the self-healing of PEDOTs:PSS films. Since flexible electronic applications of PEDOTs:PSS films are highly inseparable from various additives or post-treatment, this initial research will help to clarify and optimize the synergy between electronic and self-healing behaviors.