Adsorption of conducting polymer to high-surface-area nanoengineered cellulose fibers to facilitate rapid fabrication of highly conductive papers

Abstract

Paper is an attractive substrate for sustainable and scalable organic electronics; however, its intrinsically insulating nature, the absence of continuous electronic pathways, and the lack of control over mixed ionic-electronic transport have limited its use in electrochemical devices. Here, we nanoengineer cellulose fibers by introducing cationic charges to facilitate a high specific surface area accessible for the adsorption of functional components. We further speed up the diffusion-controlled adsorption through controlled partial fibrillation of the fibers. The combined cationic charge and high surface area enabled high adsorption of the conducting polymer PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) throughout the internal nanostructure of the fiber wall. The modified fibers were then rapidly transformed to mechanically robust, electrically conductive papers using conventional papermaking methodology. Post-treatment of papers containing 30 wt% PEDOT:PSS resulted in excellent charge transport and a conductivity as high as 13 S cm^-1. Furthermore, electrochemical impedance spectroscopy of wet papers confirmed effective mixed ionic-electronic transport. Finally, to demonstrate the possibilities of the electroactive paper, we integrated the paper as channel materials in organic electrochemical transistors and evaluate them as enzyme-free hydrogen peroxide sensors, achieving a limit of detection of 0.79 µM and a sensitivity of 8.5% per decade, highlighting the potential of combining fiber-wall engineering with scalable processing and device integration.