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Description:

Electrochromic (EC) materials and devices (ECDs) have been extensively studied, providing valuable insight into their optical switching properties and material characteristics. To analyse dynamic and subtle spatial variations during switching, we developed for the first time a non-invasive, automated, image-based methodology capable of resolving EC behavior at the pixel level. Grayscale images, extracted from video recordings at 0.0333 s intervals during cyclic operation, were segmented into 8,448 localized pixel positions to quantify contrast–time profiles. Firstly, switching non-uniformity was visualized, revealing reaction times from 0.8 to 2.0 s to reach 90% contrast change, with faster responses at the edges and slower transitions in the center. Secondly, segmental kinetics were evaluated by fitting time constants (τ) to each profile and linking them to composite resistances using a simplified RC model with a uniform areal capacitance (0.0133 F cm⁻2). The edge segment exhibited lower τ (1.79) and resistance (134.5 Ω·cm2), whereas the central pixel position showed delayed switching (1.80 s) with larger τ (2.46) and higher resistance (184.9 Ω·cm2). Finally, spatial distributions were visualized through 2D heat maps, confirming slower central regions (1.60-1.95 s), with regional average resistance 185.7 Ω·cm2 compared to lower-resistance peripheral regions (136.8–149.6 Ω·cm2). This non-invasive approach enables high-resolution diagnostic platform for quantifying uniformity, kinetics, and resistance distributions in large-area ECDs and is broadly applicable to diverse EC architectures influenced by spatial transport effects.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Electrochromic device

Date published: 2025-12-09

Publisher: American Chemical Society (ACS)

Journal:

• ACS Applied Electronic Materials (ISSN: 26376113) vol. 7 issue. 23 p. 10651-10663

Funding:

• JST-Mirai Program JPMJMI21I4
• Environmental Restoration and Conservation Agency JPMEERF20221M02

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1021/acsaelm.5c01754

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Updated at: 2026-01-07 10:31:36 +0900

Published on MDR: 2026-01-07 12:22:00 +0900