Enhanced electrochromic and mechanical properties of WO3 film by substrate effect

In the present study, the electrochromic and mechanical properties of sputtered tungsten oxide (WO3) films deposited on substrates with different surface roughness were systematically investigated. The experimental results demonstrate that tungsten oxide films, which were deposited on fluorine-doped tin oxide with a surface roughness of 21.4 nm, exhibited superior electrochromic properties. The film's optical contrast reached 77.1% not only at 700 nm. Further, the colouring and bleaching speeds were 5.7 s and 5.9 s, respectively, while the coloration efficiency reached 157.9 cm2C−1. In addition, the peak current density of FRa21 was reduced by only about 5.6% from 4.23 mA/cm2 to 3.99 mA/cm2 after about 4000 cycles, and the coloured state transmittance reduced by only 28% without power supply during a 3600 s duration. The mechanical test results show that the elastic modulus was 79.7 ± 3.82 GPa, which was lower than the others. The finite element method was applied to explore the generation and propagation of lumps and cracks observed in SEM, and the film was found to have a greater ability to resist deformation. The present study can provide a reference for improvement of electrochromic properties especially for flexible electrochromic devices.