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

: Macher, Sven; Schott, Marco; Sassi, Mauro; Facchinetti, Irene; Ruffo, Riccardo; Patriarca, Giorgio; Beverina, Luca; Posset, Uwe; Giffin, Guinevere A.; Löbmann, Peer

Volltext ()

Advanced Functional Materials 30 (2020), Nr.6, Art. 1906254, 8 S.
ISSN: 1616-301X
ISSN: 1616-3028
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer ISC ()
electrochromic polymers; electrochromism; flexible electrochromic devices; PEDOT; roll-to-roll coating

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 in terms of visible light transmittance change, Δτv = 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 blue-colored 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 Δτv = 47% (ΔL* = 51.9) and a neutral-colored bleached state is developed.