Highly Stretchable and Highly Conductive PEDOT:PSS/Ionic Liquid Composite Transparent Electrodes for Solution-Processed Stretchable Electronics

Stretchable conductive materials have received great attention owing to their potential for realizing next generation stretchable electronics. However, the simultaneous achievement of excellent mechanical stretchability and high electrical conductivity as well as cost-effective fabrication has been a significant challenge. Here, we report a highly stretchable and highly conducting polymer that was obtained by incorporating an ionic liquid. When 1-ethyl-3-methylimidazolium tetracyanoborate (EMIM TCB) was added to an aqueous conducting polymer Solution of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), it was found that EMIM:TCB acts not only as a secondary dopant but also as a plasticizer for PEDOT:PSS, resulting in a high conductivity of >1000 S cm with stable performance at tensile strains up to 50% and even up to 180% in combination with the prestrained substrate technique. Consequently, by exploiting the additional benefits of high transparency and solution-processability of PEDOT:PSS, we were able to fabricate a highly stretchable, semitransparent, and wholly solution processed alternating current electroluminescent device with unimpaired performance at 50% strain by using PEDOT:PSS/EMIM TCB composite films as both bottom and top electrodes.