Highly robust and flexible WO3·2H2O/PEDOT films for improved electrochromic performance in near-infrared region

Innovative WO3·2H2O/PEDOT films with strong adhesion of the electrochromic layer and the substrate were fabricated. A WO3·2H2O/PEDOT electrochromic layer can be firmly fixed to an ethylene vinyl acetate/polyethylene terephthalate (EVA/PET) electrode using Ag as the conductive layer by a transient heating method. The electrochromic film is mechanically robust and can be twisted, folded and crumpled without performance degeneration. Improved performance has been realized by WO3·2H2O/PEDOT films compared with WO3·2H2O films due to the excellent electrical conductivity of PEDOT, including a higher of Li-ion diffusion coefficient (1.1×10−9 cm2 s−1), faster response time (2.6 s for bleaching time and 4.4 s for coloration time), higher color efficiency (180.2 cm2 C−1) and larger transmittance modulation (63.1%) at 956 nm. The results are very promising for the next generation of deformable or implantable hidden message displays and wearable smart clothes applications.

Schematic illustration of the structure for the flexible WO3·2H2O/PEDOT films.171