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

Abstract Innovative WO 3 ·2H 2 O/PEDOT films with strong adhesion of the electrochromic layer and the substrate were fabricated. A WO 3 ·2H 2 O/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 WO 3 ·2H 2 O/PEDOT films compared with WO 3 ·2H 2 O films due to the excellent electrical conductivity of PEDOT, including a higher of Li-ion diffusion coefficient (1.1×10 −9  cm 2  s −1 ), faster response time (2.6 s for bleaching time and 4.4 s for coloration time), higher color efficiency (180.2 cm 2  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.