Enhanced Electrical Performance and Stretchability by Plasticizer-Facilitated PEDOT:PSS Self-Alignment

Stretchable, soft electronics have high potential for wearable healthcare applications and biointerfacing. One approach to render inherently brittle conductive polymers such as poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) stretchable are organic plasticizers. However, little is known on how they affect the morphology and in result the electrical properties of conductive thin-films. This study fundamentally explores this relationship using a bilayer model of transfer-printed PEDOT:PSS on stretchable, biocompatible poly(vinyl alcohol) substrates infused with glycerol (15-55 wt.%). The diffusion of the plasticizer leads to a reorganization of PEDOT and PSS, which is investigated using a multicomponent diffusion model. This approach correctly predicts the (plasticizer-dependent) increase in conductivity that followed plasticizer diffusion and is attributed to the reorganization toward more interconnected PEDOT domains. In result, the system shows an improved electrical response to strain as well as crack-free elongation. Simultaneously, the electrical resistance decreases to one-fifth of its initial value, which is attributed to chain-alignment upon strain.