Extending the Color Retention of an Electrochromic Device by Immobilizing Color Switching and Ion-Storage Complementary Layers

Monika Wałęsa-Chorab,William G Skene

doi:10.3390/electronicmat1010005

Monika Wałęsa-Chorab, William G Skene

Open Access

https://doi.org/10.3390/electronicmat1010005

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Abstract

The thermal polymerization of a bis(triphenylamine)-bis(styrene) monomer on ITO coated glass gave an electroactive film that underwent two stepwise oxidations. The perceived color change of the film upon stepwise oxidation was colorless-to-yellow followed by yellow-to-blue. The anodic cyclic voltammogram of the monomer was consistent over multiple cycles. The immobilized film could be reversibly switched between its colorless and blue states with applied potential in both a half- and full-electrochromic functioning device. The devices could also reversibly switch their colors upwards of 6 h. The retention of the electrochemically induced blue color was contingent on the device architecture. Upwards of 80% of the color was maintained 30 min after the potential was turned off with the double-layer electrochromic device structure. This device was prepared from two electroactive layers: a bis(triphenylamine) and viologen-based polymers that were immobilized on the electrodes. In contrast, 50% of the color of the active electrochromic device that was prepared from a single electroactive layer bleached 7 min once the potential was no longer applied.

Highlights

Electrochromic devices are enabled by the active layer that undergoes a substantial color shift with an applied potential
Triphenylamines in general are high performance materials that are capable of switching multiple times between their neutral and electrochemically induced colored states [14,15,16,17]
The bis(triphenylamine) monomer 1 with the two styrene units was prepared in a multistep reaction (Figure S1) similar to known means [42,43]

Summary

Introduction

Electrochromic devices are enabled by the active layer that undergoes a substantial color shift with an applied potential. Triphenylamines in general are high performance materials that are capable of switching multiple times between their neutral and electrochemically induced colored states [14,15,16,17]. This behavior is carried over into devices that sustain reversible color switching over extended periods of time. With single-layer devices that consist uniquely of one electrochromic material, the potential must be continuously applied to maintain the color of the transient state [18]. Single-layer devices can be considered as active devices in which the potential must be actively maintained for the transient color to persist.

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