Isomeric effects of poly-viologens on electrochromic performance and applications in low-power electrochemical devices

Ye Ryeong In, Hyo Jin Park, Jin Han Kwon, Yong Min Kim, Keon Woo Kim, Devesh K. Pathak, Se Hyun Kim, Seung Woo Lee, Hong Chul Moon

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Electrochromic (EC) behaviors of poly-viologens are tuned by selecting positions (ortho (o), meta (m), and para (p)) of the benzene rings linked to 4,4′-bipyridine. All-in-one type EC devices (ECDs) are conveniently fabricated by adding poly-viologens to highly conductive solid-state polymeric gel electrolytes. The maximum transmittance contrast (ΔT) of the o-poly-viologen based ECD is much lower than that of the other isomers, and its bleaching is not reversible, whereas a large ΔT and high stability are achieved with the m- and p-poly-viologens. Considering the high solubility of the m-poly-viologen in ion gels, it is anticipated to have a larger hydrodynamic size, leading to low diffusivity (∼1.1 × 10−12 cm2/s for cationic and ∼2.7 × 10−12 cm2/s for anionic current). As a result, the m-poly-viologen ECD shows a superior memory effect and long-lasting colored state without voltage supply. This feature allows us to demonstrate a low-power ECD based on the m-poly-viologen, which only requires ∼3.54 μW/cm2 to maintain the transmittance below 30%. The results indicate that adjusting the isomeric molecular structure of poly-viologen EC chromophores is an effective way to control their EC performance.

Original languageEnglish
Article number111734
JournalSolar Energy Materials and Solar Cells
Volume240
DOIs
StatePublished - 15 Jun 2022

Keywords

  • Electrochromism
  • Ion gels
  • Isomers
  • Low-power displays
  • Poly-viologens

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