Search

Tungsten oxide and titanium doped tungsten oxide thin films, deposited by sputtering, were immersed in a viscous electrolyte comprised of LiClO 4 in propylene carbonate and 2.0 wt% of polyethylene oxide (PEO). Electrochromic properties of the films were investigated by electrochemical techniques and in situ transmittance measurements. Cyclic voltammetry data were taken in the voltage ranges 2.0–4.0 and 1.5–4.0 V vs Li/Li+ for up to 500 cycles. A potentiostatic rejuvenation treatment was then performed on the degraded electrochromic films, at 6.0 V for 20 h, which was subsequently followed by another cyclic voltammetry measurement. Titanium incorporation into tungsten oxide resulted in a small cyclic stability improvement in the 2.0–4.0-V range, whereas less pronounced effects were observed for cycling in the 1.5–4.0-V range. Combining the results of the present study with our previous work, we are able to assess the relative merits of titanium incorporation and PEO addition to the electrolyte for the durability of electrochromic tungsten oxide thin films. Titanium addition was found advantageous for electrochemical durability in the 2.0–4.0-V range, but no clear benefits of PEO in the electrolyte were seen. On the other hand, in the wider 1.5–4.0-V range, tungsten oxide exhibited better durability than titanium-containing films, and this was especially so after rejuvenation in the PEO-containing electrolyte. [Display omitted] • Electrochromic durability and potentiostatic rejuvenation were studied for Ti-Woxides in polyethylene oxide electrolyte. • Films were immersed in electrolytes comprised of LiClO 4 in propylene carbonate and 2.0 wt% of polyethylene oxide. • Film degradation was investigated in ranges between 1.5–4.0 and 2.0–4.0 V vs. Li/Li+. • Ti incorporation resulted in improvement of stability in potential range 2.0–4.0 V. [ABSTRACT FROM AUTHOR]

Electrochromic (EC) technology allows control of the transmission of visible light and solar radiation through thin-film devices. When applied to "smart" windows, EC technology can significantly diminish energy use for cooling and air conditioning of buildings and simultaneously provide good indoor comfort for the buildings' occupants through reduced glare. EC "smart" windows are available on the market, but it is nevertheless important that their degradation under operating conditions be better understood and, ideally, prevented. In the present work, we investigated EC properties, voltammetric cycling durability, and potentiostatic rejuvenation of sputter-deposited WO 3 thin films immersed in LiClO 4 –propylene carbonate electrolytes containing up to 3.0 wt% of ∼7-nm-diameter SiO 2 nanoparticles. Adding about 1 wt% SiO 2 led to a significant improvement in cycling durability in the commonly used potential range of 2.0–4.0 V vs. Li/Li+. Furthermore, X-ray photoemission spectroscopy indicated that O–Si bonds were associated with enhanced durability in the presence of SiO 2 nanoparticles. [Display omitted] • Electrochromic properties, durability, and potentiostatic rejuvenation of W oxide thin films are investigated. • The aim was to study the effect of ∼7-nm-diameter silica nanoparticles in LiClO 4 –propylene carbonate electrolytes. • Film degradation was investigated in range between 2.0 and 4.0 V vs. Li/Li+. • Adding about 1 wt% SiO 2 led to a significant improvement in cycling durability. • O–Si bonds were associated with enhanced durability in the presence of SiO 2 nanoparticles. [ABSTRACT FROM AUTHOR]

Thin films of electrochromic (EC) W oxide were prepared by reactive DC magnetron sputtering and were immersed in electrolytes of LiClO 4 in propylene carbonate with 0.5–3.0 wt% of added polyethylene oxide (PEO). Charge density and optical modulation range were found to diminish monotonically upon prolonged voltammetric cycling with concurrent optical transmittance measurements for up to 500 and 200 cycles in the voltage ranges 2.0–4.0 and 1.5–4.0 V vs. Li/Li+, respectively. Rejuvenation of the degraded EC films was then accomplished by potentiostatic treatment at 6.0 V vs. Li/Li+ for 20 h and has been ascribed to expulsion of trapped Li ions. Importantly, degradation subsequent to rejuvenation was found to progress at a significantly lowered pace than for as-deposited films—in proportion with the amount of PEO—especially for harsh voltammetric cycling in the voltage range 1.5–4.0 V vs. Li/Li+. The results of this explorative study are of considerable value for the development of highly durable EC devices such as polymer-laminated smart glazing for energy efficient buildings with excellent indoor comfort. • Potentiostatic rejuvenation of electrochromic WO 3 thin films was studied. • Films were immersed in electrolytes of LiPC with 0.5–3.0 wt% of added polyethylene oxide. • Film degradation was investigated in potential ranges of 1.5–4.0 and 2.0–4.0 V vs. Li/Li+. • The addition of PEO led to significant improvements of stability in the potential range 1.5–4.0 V. • Optical properties after rejuvenation are best for PEO concentrations in the range 1.5–2.5 wt%. [ABSTRACT FROM AUTHOR]