Electrochromic properties of W1–x–yNixTiyO3 thin films made by DC magnetron sputtering

•We report our results concerning Ni–Ti incorporation on W oxide electrochromic films.•The presence of Ti in W1–x–yNixTiyO3 electrochromic thin films increase electrochemical cycling durability.•High concentration of Ni in W0.83–xNixTi0.17O3 is detrimental to the electrochromic performance.

We investigated the electrochromic properties of tungsten–nickel–titanium oxide (W1–x–yNixTiyO3) thin films. Special emphasis was put on W0.83–xNixTi0.17O3 since this composition gave the highest electrochemical durability. The films were deposited onto indium–tin oxide coated glass by reactive DC magnetron sputtering, and cyclic voltammetry as well as optical transmittance measurements were performed in an electrolyte of 1 M LiClO4 in propylene carbonate. The potential window was chosen so as to cause rapid degradation of the samples. Elemental compositions were obtained by Rutherford backscattering spectroscopy and structural information by X-ray diffraction. We verified that the titanium additive improved the electrochemical durability of tungsten-oxide-based films and also documented that a further addition of nickel was unable to enhance the EC performance to any significant degree.