Flexographically Printed PEDOT:PSS Electrodes Enabling Stable Paper-Based Self-Powered Electrochromic Devices

The performance and scalability of electrochromic devices (ECDs) are highly dependent on the architecture and uniformity of their electrodes. However, conventional coating or printing approaches restrict the controllable patterning and large-scale fabrication required for sustainable paper-based ECDs. In this study, a high-quality PEDOT:PSS electrode was fabricated using roll-to-roll (R2R) flexographic printing, offering a scalable and low-cost route for flexible electrochromic manufacturing. The rheological behavior of the ink was characterized to elucidate its influence on film formation and electrical conductivity on biodegradable paper substrates. The assembled self-powered paper-based ECD exhibited a maximum optical contrast of 0.27 at 650 nm, a coloration efficiency of 70.4 cm 2 C –1, and excellent cycling durability with 97.7% optical stability after 12,000 s of switching. Moreover, the printed electrodes enabled precise and uniform patterning with reversible deep-to-light blue transitions. This work establishes a green and designable fabrication strategy for sustainable, high-performance paper-based ECDs, paving the way for next-generation flexible and eco-friendly optoelectronic systems.