Fast printing of thin, large area, ITO free electrochromics on flexible barrier foil

Abstract

Processing of large area, indium tin oxide (ITO) free electrochromic (EC) devices has been carried out using roll‐to‐roll (R2R) processing. By use of very fine high‐conductive silver grids with a hexagonal structure, it is possible to achieve good transparency of the electrode covered substrates and when used in EC devices switching times are similar to corresponding ITO devices. This is obtained without the uneven switching of larger areas, which is generally observed when using ITO because of its high‐sheet resistance. The silver electrode structures for 18 × 18 cm2 devices can be processed at high speed (10 m/min) on PET by flexographic printing and the EC polymer ECP‐Magenta as well as a minimal color changing polymer MCCP by slot‐die coating, showing the potential for fast fabrication of large volumes of low‐priced flexible EC devices by use of R2R processing techniques. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013

Fast Switching ITO Free Electrochromic Devices

“…[ 17,20 ] A second obstacle in using MCCP in combination with the silver grid electrodes is the blooming effect previously reported and shown in Figure 1 A. [ 10 ] As the areas between the grid lines are non-conductive, the hexagonal grid structures result in an inhomogeneous electrical fi eld between the two electrodes. This requires lateral charge transport for redox switching to occur, and the results is a slow uneven switching, as shown in Figure 1 A.…”

“…[ 17,27 ] As the name implies MCCP lends limited absorption to the visible region and we have previously made use of this polymer as a counter polymer in ECDs, due to good solubility and processing properties that allows a wide range of coating applications. [ 10,20 ] These properties qualifi ed MCCP to be one of the best choices as counter polymer for a grid based device. Unfortunately, we found that employing MCCP in a fl exoprinted grid based device produced a slight reddish taint following repeated switches at -1 V to +1 V. By carefully taking the device apart, the discoloring was found to reside on the electrode coated with MCCP.…”

“…Such grids have been utilized as counter electrodes in inorganic based ECDs, and we have previously shown how ITO can be replaced by fl exoprinting a silver based conductive hexagonal grid onto a transparent polyethylene terephthalate (PET) substrate. [ 5,10 ] Other reports show successful substitution of ITO by organic semiconductors (mostly poly(3,4-ethylenedioxythiophene), PEDOT) for fabrication of all-organic or fully printable ECDs. [11][12][13][14] Development of ITO free ECDs is an interesting academic accomplishment, as well as a major cost reducing factor, in line with our development of commercially attractive ECDs; combining fl exibility, effi cient production, high operational stability and good electrochromic properties.…”

Flexible, Switchable Electrochromic Textiles

“…Also, any even minor damage usually requires the replacement of the entire device. At this point, flexible , foil‐ or textile‐based electrochromic materials represent an appealing, cheaper alternative, because these materials can be integrated far better than glass, offer many more options with regards to interior design and repair and have a by far lower weight. Here, we present our approach, which transfers the principles of electrochromism from glass to flexible textile‐based materials.…”

Printed passive matrix addressed electrochromic displays

“…Major efforts are currently being devoted to explore and develop new devices and systems for printed electronics applications [1][2][3][4][5][6][7]. The theme of this effort aims at providing novel electronic functionalities on flexible substrates such as plastic foils or papers.…”