Paper‐Based Electrochromic Devices Enabled by Nanocellulose‐Coated Substrates

Abstract

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 Ω 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 (ΔE*) of 56 owing to a highly color-neutral bleached state of the ECP (a* = −0.5, b* = 2.9). Black-tocolorless devices achieve ΔE* = 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 Ω sq −1 ). The paper ECDs are then combusted in air leaving 3% of the initial mass at 600 °C, highlighting this approach as a promising route toward disposable displays. Figure 2. Optimization of printed electrodes showing a) reflectance as a function of sheet resistance for printed electrodes on glass, CNF coated paper, and office paper. Photographs of PEDOT:PSS electrodes on CNF coated paper with sheet resistances of b) 5000 Ω sq −1 , c) 460 Ω sq −1 , d) 160 Ω sq −1 , and e) 109 Ω sq −1 . CIELAB color coordinates are labeled below each image. www.afm-journal.de www.advancedsciencenews.com 1903487 (4 of 11)

A high-conductivity n-type polymeric ink for printed electronics

“…This mixed ion-electron conductor owes its success to a high electrical conductivity, spanning over several orders of magnitude and reaching values >1000 S cm −1 , an excellent ambient stability, and commercial availability as aqueous dispersions for processing via traditional coating and printing techniques 6 . Today, PEDOT: PSS has been employed as the charge extraction/injection layer in organic solar cells 7,8 and light-emitting diodes 9,10 , as well as the active material in electrochromic displays 11,12 , actuators 13,14 , electrochemical transistors [15][16][17] , sensors 18,19 , supercapacitors 20,21 , stretchable electronics 22,23 , thermoelectrics [24][25][26] , and brain-inspired memories 27,28 . However, many opto-and bioelectronic devices and systems rely on the complementarity of both high-performance hole-transporting and electron-transporting (n-type) materials.…”

High Thermoelectric Performance in n‐Type Perylene Bisimide Induced by the Soret Effect

“…While an inorganic mixed conductor can be crystalline, the organic mixed conductors reported to date are typically amorphous, [ 29 ] and very little has been done for the characterization of their thermoelectric properties. The polymer blend composed of PEDOT as the hole conductor and PSS as the cation conductor is a typical mixed conductor used in many electrochemical devices, such as electrochromic displays, [ 30 ] supercapacitors, [ 31 ] and transistors. [ 32 ] PEDOT:PSS possesses an ionic conductivity of 0.03 S cm −1 at 80% RH, which is one order of magnitude lower than the electronic conductivity (0.3 S cm −1 at 80% RH).…”

TiO2 Nanostructured Films for Electrochromic Paper Based-Devices

“…Other studies also reported the switch behavior of paper EC devices. Lang et al [30] demonstrated EC devices with paper-based substrates and printed poly-(3,4ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) electrodes showing slower switching time when produced with a lateral device architecture. Tehrani et al [32] reported PEDOT:PSS-based EC displays with an extra layer of dihexyl-substituted poly(3,4-propylenedioxythiophene) (PProDOT-Hx2) and using flexible paper substrates in roll-to-roll printing.…”

“…The EC materials are largely integrated in smart windows, displays and mirrors, however the demand for flexible devices has been gradually growing in the recent years, especially due to their conformability characteristic to unlike surfaces and the need to reduce production costs [29]. In this sense, electronics on paper appears as an attractive option as cellulose is the most abundant biopolymer on earth, inexpensive and guarantee highly flexibility to the device, despite being environmentally friendly [30]. In fact, paper has been included in several optoelectronic devices, including solar cells, transistors, among others [30,31], and lately paper started to appear as a reliable alternative for EC devices, as previously reported in [30,[32][33][34].…”