Electrochromism of W–In oxide thin films: Implications for cycling durability

• Published in: Thin solid films 2020-03, Vol.697, p.137830, Article 137830
• Main Authors: Sorar, Idris, Pehlivan, İlknur Bayrak, Granqvist, Claes G., Niklasson, Gunnar A.
• Format: Article
• Language: English
• Subjects: Cycling durability; Electrochromism; Engineering Science with specialization in Solid State Physics; Indium oxide; Sputter deposition; Teknisk fysik med inriktning mot fasta tillståndets fysik; Thin films; Tungsten oxide; Tungsten oxide, Indium oxide
• ISSN: 0040-6090; 1879-2731; 1879-2731
• DOI: 10.1016/j.tsf.2020.137830

•Electrochemistry of W oxide and W–In oxide thin films were studied.•Film degradation was investigated in ranges between 1.5–4.0 and 2.0–4.0 V vs. Li/Li+.•Indium doping was found to be detrimental to electrochromic cycling durability.•The data resolve an important issue for electrochromic durability of WO3/ITO films.•It demonstrates the critical importance of carbonaceous surface layers. Electrochromic W oxide and W–In oxide thin films were prepared by dual-target reactive DC magnetron sputtering and were cycled voltammetrically in an electrolyte of lithium perchlorate in propylene carbonate. Film degradation was investigated for up to 500 cycles in the voltage ranges 1.5–4.0, 1.7–4.0 and 2.0–4.0 V vs. Li/Li+, and optical transmittance was recorded concurrently. Indium doping was found to be unambiguously detrimental to electrochromic cycling durability, which resolves an outstanding issue related to recently discovered unprecedented durability of potentiostatically pretreated W oxide films backed by In2O3:Sn and gives strong support in favor of beneficial effects of solid-electrolyte interfacial layers.