Pure, 5% Ti-doped and 10% Ti-doped WO3 thin films were prepared by the radio frequency magnetron sputtering and characterised by a SEM, an electrochemical workstation and an UV–VIS–NIR spectrophotometer. Research results showed that Ti doping had no apparent influence on the surface morphology and optical band gap. It could also be found that the addition of Ti has little interference with the electrochromic property of WO3 in both bleached and coloured states at initial cycles from electrochemical and optical test results, while there were apparent differences in the optical transmittance and inserted and extracted charge with increasing cycles. This is attributed that Ti-doped WO3 thin films allow facile ion interaction/extraction and have less ion residues, which can stabilise the electrochemical cycling performance. Furthermore, the data we have obtained indicate that 5% Ti-doped WO3 film has the best electrochromic property.
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