Effects of phase and morphology on the electrochromic performance of tungsten oxide nano-urchins

We report on the electrochromic performance of the novel crystalline tungsten oxide nano-urchins comprised of the W18O49 nano-wires added to the sphere shell. The performance of electrochromic devices was systematically compared by using tungsten oxide nano-structures with and without nano-wires on the surface of nano-sphere and with different phase of W18O49 and WO3. The optimized electrochromic films with nano-urchin-like W18O49 exhibited a fast switching response time, outstanding high coloration efficiency (∼132 cm2/C), and durability within acidic electrolyte. This performance can be attributed to the high volume to surface ratio and phase of uniform urchin-like tungsten oxides.