Electrochromic Ni–Fe oxide thin films synthesized by an atmospheric pressure plasma jet for flexible electrochromic application

•Rapid deposition of electrochromic organo-nickel–iron oxide (NiFexOyCz) films•Enhanced electrochromic performance of NiFexOyCz films by oxygen gas addition•Uniform light modulation on NiFexOyCz films produced by air plasma jet•Porous surfaces allow reversible Li+ intercalation and deintercalation.

Flexible-electrochromic organo-nickel-iron oxide (NiFexOyCz) films deposited onto flexible polyethylene terephthalate (PET)/indium tin oxide (ITO) substrates using atmospheric-pressure plasma-enhanced chemical vapor deposition with an atmospheric pressure plasma jet under various flow rates of oxygen gases are investigated. Precursors [nickelocence, Ni(C5H5)2] and [ferrocence, Fe(C5H5)2] vapors are carried by argon gas, mixed by oxygen gas and injected into air plasma torch for a rapid synthesis of NiFexOyCz films by a short duration of the substrate, 32 s, in the plasmas. Uniform light modulation on PET/ITO/NiFexOyCz is produced while the moving PET/ITO substrate is exposed to plasma torch at room temperature (~ 23 °C) and atmospheric pressure. Light modulation with up to a 43.2% transmittance variation at a wavelength of 708 nm even after 200 cycles of Li+ intercalation and de-intercalation in a 1 M LiClO4-propylene carbonate electrolyte is accomplished.