Paper-Based Electrochromic Devices Enabled by Nanocellulose-Coated Substrates

As environmental considerations for both the processing and disposal of electronic devices become increasingly important, the ability to replace plastic and glass substrates with bioderived and biodegradable materials remains a major technological goal. Here, the use of cellulose nanofiber-coated paper is explored as an environmentally benign substrate for preparing low-resistance (460 omega sq(-1)), colorless (a* = -2.3, b* = -2.7) printed poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) electrodes. The PEDOT:PSS/paper electrodes support the reversible oxidation of three electrochromic polymers (ECPs) (cyan, magenta, and yellow), affording the possibility for fully printed, color displays on paper. Lateral electrochromic devices (ECDs) incorporating an ion gel electrolyte are demonstrated where a magenta-to-colorless device achieves a color contrast (Delta E*) of 56 owing to a highly color-neutral bleached state of the ECP (a* = -0.5, b* = 2.9). Black-to-colorless devices achieve Delta E* = 29 and are able to retain 86% of their color contrast after 9000 switches. The switching times of these lateral devices are quantified through colorimetric image analysis which shows comparable performance for devices constructed on paper as devices using ITO/glass electrodes (10 omega sq(-1)). The paper ECDs are then combusted in air leaving 3% of the initial mass at 600 degrees C, highlighting this approach as a promising route toward disposable displays.