Structural, morphological, optical and electrochromic properties of Ti-doped MoO₃ thin films

Thin films of molybdenum trioxide (MoO₃) doped with titanium were prepared using a spray pyrolysis technique. Increasing Ti doping concentration was found to hamper the polycrystalline nature of undoped orthorhombic MoO₃ and undergo transformation from polycrystalline to amorphous structure with decrease in grain size. This was also reflected in scanning electron microscopy wherein transformation of thread-like reticulated morphology to spongy structures could be observed at higher Ti concentration (9 at% Ti). With increasing Ti concentration, the charge capacity, coloration efficiency, reversibility and electrochemical stability increased. This improvement could be ascribed to the amorphous spongy morphology of the doped samples that offers easy pathway for intercalation and deintercalation of the ions. Hence, 9 at% Ti-doped MoO₃ can act as an adequate host for electrochromic devices.