Design and fabrication of bimodal meso-mesoporous WO₃ thin films and their electrochromic properties

Based on a novel, facile and reliable two-step coating process, tungsten oxide films (TOFs) with bimodal mesoporous-mesoporous structure (BMM) were designed and realised in terms of a bilayered mesostructural configuration. The key step for successful fabrication of these BMM TOFs is the selective thermal sensitisation of the tungstic acid/Brij 56 derived sol-gel TOFs by different chemical modification to the inorganic tungsten oxide species. Moreover, one striking advantage of this process lies in that it also allows delicate tailoring of the resulting BMM structures by simple heat-treatment at different temperatures. According to the initial test results on the electrochromic properties, the obtained BMM TOFs demonstrate superior performance over their monomodal counterparts.