Nanoparticulate films of WO₃ and MoO₃ composites for enhancing UV light electrochromic transmittance variation and energy storage applications

Green technologies for the manufacture of optical shutters retain a sustainable development. In this work, the electro-exploding wires and spray coating technologies are employed to deposit nanoparticulate (WO₃)_1-x(MoO₃)_x composite films. MoO₃ NPs are introduced to enhance electrochromic (EC) transmittance variation of violet and UV light with wavelengths ranging from 330 to 450 nm. Measurements of EC performances of (WO₃)_1-x(MoO₃)_x composite films in a potentiostat are carried out to discern beneficial from MoO₃ addition. It is observed that the diffusion coefficient and the charge density increase with an increment of MoO₃ concentration. The coloration efficiency at 430 nm raises apparently whereas that at 633 nm does not show a significant variation with increasing MoO₃ concentrations. In addition, the EC device with ∼12.5% of MoO₃ introduced reveals a much higher optical modulation at 430 nm. From the measurements of galvanostatic charge-discharge curves of EC films in the potentiostat, the areal capacitances of 12.9 and 14.0 mF/cm² are estimated for pure and ∼12.5% MoO₃ introduced WO₃ EC films. The EC batteries are demonstrated and the enlarged energy storage capability with an addition of MoO₃ is observed. The simple introduction of MoO₃ into WO₃ nanoparticulate films compensates drawbacks of WO₃ films and enhances EC performances and energy storage capabilities.