Enhanced lithium electrochromic performance of flexible tungsten oxide films by the addition of tantalum with an atmospheric pressure plasma jet in a rapid synthesis onto flexible 40 Omega/square polyethylene terephthalate/indium tin oxide substrates was investigated. The flexible organic-inorganic hybrid composites WOyCz, WTaxOyCz and TaOyCz, films were synthesized by injecting the precursors tungsten carbonyl [W(CO)(6)] and/or tantalum ethoxide [Ta(OC2H5)] into an air plasma jet under an atmospheric pressure and the ambient temperature (similar to 23 degrees C). The addition of tantalum into tungsten oxide films improves the optical modulation (Delta T) from 62.3% to 74.8% (at a wavelength of 800 nm, even after 200 cycles of reversible Li+ ion intercalation/de-intercalation in a 1 M LiClO4-propylene carbonate electrolyte), reduces the coloration time from 13 s to 8 s, and increases the diffusion coefficient of the lithium ion from 0.4 x 10(-10) cm(2)/s to 1.2 x 10(-10) cm(2)/s. (C) 2013 Elsevier B.V. All rights reserved.