2009 年 60 巻 4 号 p. 268
Amorphous WO3·nH2O thin films were deposited at room temperature on Si and ITO/glass substrates. After mixing Na2WO4 solution and HCl solution, they were dripped immediately on a rotating substrate to produce a deposited film. This process is simple and applicable to a non-heat resistant substrate. Furthermore, it might be preferable for producing electrochromic (EC) properties of WO3 thin film because the film obtained at room temperature contains OH group. The optimum film deposition parameters are as follows: Na2WO4 solution, 1.0 mol·dm−3; HCl solution, 1.0 mol·dm−3; flow rate, 2.0 mL·min−1; pH: 0.2. The films obtained under the optimum parameters had a composition of WO3·(2.6-2.7)H2O and displayed good adhesion and scratch hardness (pencil method > 9H). The thin films obtained using this method exhibit excellent EC properties of color efficiency (45-50 cm2·C−1), and response time (3 V, 2 s, ΔT = 50%).