Conductive Free Standing Polymer Paste Synthesized by Acid Induced Phase Separation

PEDOT:PSS is one of the most studied and used polymers. The current literature shows that this material is employed in solar cells, electrochemical cells, devices for energy storage and stretchable electronics. However films with thickness in the scale of hundreds of nanometres have the intrinsic limitation that must be deposited onto a solid and consistent substrate, thus leading to bulky devices. Moreover pristine PEDOT:PSS exhibits low conductivity and thus several treatments, such as drop casting or acid vapours exposure, are usually pursued to increase it. These methods however are not easily implementable in production lines. Here we show a freestanding conductive dark-PEDOT (d-PEDOT), obtained by a low cost and fast in-solution treatment by sulphuric acid. The proposed synthesis procedure is based on methods industrially implementable. The obtained paste is mouldable and allows for the fabrication of free-standing tens of μm thick foils, made as easily as scribing by an ink pen. Electrical characterization shows a conductivity of 500 Scm−1, which makes the new material a good alternative to standard and expensive metal contacts.