High-performance embedded nickel grid electrodes for fast-response and bendable all-solid PEDOT: PSS electrochromic devices

Electrochromic devices are emerging as a futuristic technology for flexible electronics with the practical application values in energy-saving, displaying and military camouflage, however, the limitations in the optical, electrical and mechanical properties of the existing transparent conducting electrodes (TCEs) appear as a major obstacle for realizing high performance flexible electrochromic devices. In this work, we have proposed and demonstrated a fast-response and bendable polymer poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT: PSS) electrochromic device based on the embedded nickel (Ni) grid electrode. The Ni grid electrode, fabricated though patterned electroplating, has low sheet resistance (~1.3 Ω/sq), high transparency (~80%), excellent mechanical reliability and long-term chemical stability, exhibiting a figure of merit of 1250, surpassing the most existing TCEs. In addition, we have proposed a compact electrochromic architecture with the electrochromic PEDOT: PSS layer and solid polymer electrolyte being sandwiched between two embedded Ni grid electrodes. The device shows a short coloration and bleaching time (~1 s for 90% optical contrast), a high coloration efficiency (325 cm 2 /C) and excellent mechanical reliability (optical contrast retention ~80% after 1000 bending circles), paving a way for high performance flexible electronics.