Synergistic roughness and plasma-driven interface engineering of spray-pyrolyzed electrochromic NiO films for enhanced electrochemical activity and stability

초록

Synergistic effect of film roughness and plasma-driven interface engineering of spray-pyrolyzed electrochromic (EC) NiO films, was investigated. This paper reports a complementary electrochromic device (CECD) combining cathodic WO3 and anodic NiO films deposited using a scalable spray technology: nanoparticle deposition system and spray pyrolysis. The spray process yields rougher film surfaces, exhibiting a high roughness-to-thickness ratio of 5–15%. This practically increases the electrochemical reaction surface area of NiO thin film to 138 cm2, accelerating its ion transport. In parallel, O2 plasma treatment on the substrate prior to NiO deposition enriches the surface oxygen-containing groups, strengthening the interfacial stability and improving the crystallinity of the NiO film. The resulting device achieves 58% optical contrast (ΔT) under low-voltage application of −2.0 V and retains 94% of its performance up to 2000 cycles. It also exhibits ultrafast coloring in. 1.8 s without the need for complex functional materials. Moreover, a 6 × 6 cm2 large-area device was fabricated, underscoring the scalability of the proposed approach. These findings bridge the gap between laboratory- and large-scale fabrication using simple spray technologies and pave the way for commercially viable EC smart windows in modern buildings. © 2026 Elsevier B.V.

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