Electrochromic properties of lithium flexible devices based on tungsten and vanadium-titanium oxide thin films

In this work we report on the optimization of the composition of vanadium and titanium mixed oxide thin films in respect with their electrochromic properties on a flexible ITO/PET substrate. Three compositions were investigated -V2O5, V(75%)-Ti(25%)-O and V(50%)-Ti(50%)-O- in the scope of their utilization as counter-electrodes against a flexible WO3/ITO/PET primary electrode, for the fabrication of (8x6 cm(2)) laminated lithium electrochromic devices. A preliminary study showed that the equimolar V/Ti ratio exhibits the best electrochemical capacity and coloration neutrality. Once assembled, this counter-electrode yielded the most performing electrochromic device after 200 cycles, with an optical contrast of 4:1 at 550 nm, an efficiency of 40 cm(2)/C with response times of coloration and bleaching in the order of the minute.