Electrochromic tungsten oxide films prepared by sputtering: Optimizing cycling durability by judicious choice of deposition parameters

Abstract Thin films of W oxide were prepared by reactive DC magnetron sputtering (5 cm-diameter target), and their electrochromic (EC) properties investigated in an electrolyte LiClO4 propylene carbonate. The purpose the study was to elucidate role critical deposition parameters—oxygen/argon gas flow ratio for sputter plasma ?, total pressure ptot, power Ps—on EC performance with foci on electrochemical cycling durability optical modulation range ?T. Specifically, we used 0.15 ? ? ? 0.90, 5 ? ptot ? 30 mTorr, 200 ? Ps ? 400 W studied up 500 voltammetric cycles 2.0–4.0 V vs. Li/Li+ together at a wavelength 528 nm. Most significantly, discovered that judicious choice parameters could yield superior durability. Thus ~300 nm-thick film ? = 0.90, ptot = 10 mTorr, Ps = 200 W showed ?T ? 65% after initial “training” during ~100 cycles; higher values other hand, yielded whose ?Ts degraded ~10% cycling, lower value ptot led dark only marginal electrochromism. Hence our work delineates pathway towards excellent properties.