Roll-to-Roll Oxidative Chemical Vapor Deposition of Highly Conductive and Uniform Thin Films on Large-Scale Textile Substrates

Abstract

A continuous vapor deposition process is demonstrated for organic conductive surface modification of large-area textile substrates. Transparent and conductive poly(3,4-ethylenedioxythiophene) (PEDOT) films were deposited by oxidative chemical vapor deposition (oCVD) technique on polyethylene terephthalate (PET) fabrics in a roll-to-roll fashion, in which as-deposited PEDOT films had excellent thickness and structural uniformity across very large areas (2 × 250 cm). We designed a continuous vacuum deposition system, in which the feeding and wrapping units of the system were in the open air, thanks to the specially designed fabric feedthroughs in and out of the vacuum system. The pristine fabric was fed into the oCVD vacuum reactor by unreeling from the outside atmosphere, where it was pretreated with oxidant iron(III) chloride (FeCl₃) solution. The effect of rolling speed of the fabric on the structure, morphology, uniformity, and electrical conductivities of the as-deposited PEDOT films were studied. FTIR and SEM analyses were carried out to verify the structure and morphology of as-deposited PEDOT films. Uniform and conformal PEDOT films with measurable conductivity were observed independent of the rolling speed. The highest conductivity value of 803.5 S/cm was observed for the films deposited at a rolling speed of 8 cm/min and doped with Cl^– ions from a 3.5 wt.% HCI solution.