A practical approach for generation of WO3-based flexible electrochromic devices

We managed to provide one-step facile electrochromic device (ECD) preparation to incorporate two cathodic coloring components into lithium ion (Li+)-doped UV-curable electrolyte. The hybrid-based flexible ECDs were fabricated by using tungsten trioxide (WO3) and poly(3,4-ethylenedioxythiophene) (PEDOT) as electrochromic components without the need for deposition procedures. The influences of lithium salts (lithium perchlorate (LiClO4) and lithium trifluoromethanesulfonate (LiTRIF)) on the electrochromic performance of flexible ECDs were evaluated. The electrochromic and the intrinsic kinetic features of all ECDs were investigated via transmittance and electrochemical impedance measurements. The ECD fabricated from LiClO4 electrolyte exhibited the highest optical transmittance modulation of 38.7% under an applied potential of +/- 2 V. To evaluate the mechanical robustness of the flexible ECDs, a bending cycle test was also conducted. After performing repetitive bending cycle tests, the optical modulation of ECD fabricated from LiTRIF electrolyte was remained stable for applied potentials of +/- 2 V. Especially, the flexible ECDs prepared from LiTRIF showed high mechanical bendability.