New Roll‐to‐Roll Processable PEDOT‐Based Polymer with Colorless Bleached State for Flexible Electrochromic Devices

Abstract

Conjugated electrochromic (EC) polymers for flexible EC devices (ECDs) generally lack a fully colorless bleached state. A strategy to overcome this drawback is the implementation of a new sidechain-modified poly(3,4-ethylene dioxythiophene) derivative that can be deposited in thin-film form in a customized high-throughput and large-area roll-to-roll polymerization process. The sidechain modification provides enhanced EC properties interms of visible light transmittance change, Δτ v = 59% (ΔL* = 54.1), contrast ratio (CR = 15.8), coloration efficiency (η = 530 cm² C −1 ), and color neutrality (L* = 83.8, a* = −4.3, b* = −4.1) in the bleached state. The intense bluecolored polymer thin films exhibit high cycle stability (10 000 cycles) and fast response times. The design, synthesis, and polymerization of the modified 3,4-ethylene dioxythiophene derivative are discussed along with a detailed optical, electrochemical, and spectroelectrochemical characterization of the resulting EC thin films. Finally, a flexible see-through ECD with a visible light transmittance change of Δτ v = 47% (ΔL* = 51.9) and a neutral-colored bleached state is developed.

Tailoring Conducting Polymer Interface for Sensing and Biosensing

“…In some cases, the side chain in the EDOT derivative is favourable for the formation of nanostructures with the template-free approach, such as the formation of tube array by using EDOT-OH 100 . In addition, the π-conjugation and energy band gap of the PEDOT backbone can be tuned by the side chain which results in modulation of the optical and electrical properties 100,109 . What is more, the wettability (hydrophobicity/hydrophilicity) of PEDOT derivative surface can be controlled by the long hydrophobic (e.g.…”

Electrochromic Polymer Ink Derived from a Sidechain‐Modified EDOT for Electrochromic Devices with Colorless Bright State

“…Conjugated electrochromic polymers (ECPs), such as poly(3,4‐ethylene dioxythiophene) (PEDOT) and its derivatives are one of the main classes of materials exhibiting EC properties as thin films [3,4,5] . The introduction of solubilizing chains with tailored steric properties, electron donating or withdrawing substituents and copolymerization with intrinsically electron poor units allow a wide range of vivid colors, the possibility of either a color change (e. g. blue to red [6] ) or a decoloration (e. g. blue to colorless [7] ), response times in the range of seconds and high coloration efficiencies [8,9–13] . While moving from the laboratory to the production‐scale, suitable EC performance has to be matched with simplicity of synthetic access, compatibility with high‐throughput deposition techniques, straightforward integration into devices and sustainability of the overall process.…”

“…This is the result of the introduction of a terminal double bond at the end of a lateral hexyl side chain (PEDOT‐EthC6). Such a functionality is believed to promote a more pronounced π‐stacking between neighboring conjugated polymer chains in the oxidized form, resulting in a complete localization of the polaronic and bipolaronic absorption in the NIR region [7,20,21] …”

“…Table 1 compares the EC performance of a series of notable ProDOT and PEDOT derivatives, including the terminal double bond bearing PEDOT‐EthC6 [7] . A fair comparison between the best ProDOT derivative and PEDOT‐EthC6 also has to take into account large‐scale processing with industrial relevant roll‐to‐roll (R2R) coating and printing machines.…”

Electrochromic Metallo–Organic Nanoscale Films: A Molecular Mix and Match Approach to Thermally Robust and Multistate Solid‐State Devices

“…[2,3] Several types of electrochromic materials (ECMs) have been reported, such as metal oxides, organic small molecules, conducting polymers, and metallo-supramolecular polymers. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] However, only a few electrochromic products are commercially available, mainly due to their long response times as well as stability and fabrication-related issues. Liquidgel electrolytes can result in poor stability because of possible side reactions and leakage.…”