Low Temperature Annealing Improves the Electrochromic and Degradation Behavior of Tungsten Oxide (WOx) Thin Films

5 years ago

Low Temperature Annealing Improves the Electrochromic and Degradation Behavior of Tungsten Oxide (WOx) Thin Films

Liam Trimby, Kunyapat Thummavichai, C. David Wright, Yanqiu Zhu, Yongde Xia, Nannan Wang

This research aims to understand the fundamental aspects of annealing on the electrochromic performance of tungsten oxides, using as-synthesized W₁₈O₄₉ substoichiometric bundled nanowires benchmarked against commercial WO₃ nanoparticles. Linking detailed structural analyses with the electrochromic measurement results, we have investigated the electrochromic performance effects of low temperature annealing, up to 350 °C, on tungsten oxide (WO_x) thin films, trying to establish the fundamental heat treatment–structure–performance loop. We have found that the annealing treatment at low temperature improved the optical modulation and long-term durability of the WO_x thin films, without changing the structure and morphology of the as-synthesized samples. The 350 °C annealing was found to have the best stability improvement for the WO₃ nanoparticle films during the electrochromic assessments, with a 4% improvement for Li⁺ intercalation and a 12% improvement for deintercalation, compared with the untreated WO₃ samples. Further improvements have been achieved for the W₁₈O₄₉ nanowire thin films, with a stability improvement of 36% for Li⁺ intercalation and 60% for deintercalation against the as-prepared W₁₈O₄₉ nanowire samples during the electrochromic performance testing.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b06300

DOI: 10.1021/acs.jpcc.7b06300