Foldable electrochromic NiO films

Foldable electrochromic NiO films were achieved through plasma enhanced e-beam evaporation on indium-doped tin oxide coated polyethylene naphthalate two formic acid glycol ester substrates. These films displayed fast coloration and bleaching times of 3.3 and 0.5 s, respectively, and were highly transparent in the visible region. The electrochromic properties of the films were evaluated using cyclic voltammetry, chronoamperometry, and spectrophotometry in an aqueous alkaline electrolyte of 0.1 M KOH. The films exhibited a coloration efficiency of 23.1 cm2/C at 550 nm. The films maintained their functionality even after being folded 1000 times under concave conditions.