Electrochromic Displays Manufactured by a Combination of Vapor Phase Polymerization and Screen Printing

Abstract

While only PEDOT:PSS devices are incorporated in these commercialized displays, many other conductive polymers possess interesting electrochromic properties that could be commercialized. [3] Recently Shin et al. incorporated a combination of conductive polymers to fabricate electrochromic displays with a near black state when the device was exposed to a voltage of 2 V. [4] Other research avenues have included developments into new electrochromic polymers to extend the range of the electrochromic switch, adjust the colors exhibited or shorten the switching time. [5][6][7] Unfortunately, due to their insoluble nature, most conductive polymers are difficult to include in inks for large scale deposition using printing techniques. PEDOT:PSS is unique in its combination to achieve a dispersive colloidal solution that can be used in functional inks for displays and other technologies. [8,9] However, a polymerization technique coined vapor phase polymerization (VPP) has allowed the production of conductive polymers in thin film form from their monomer vapors. [10,11] The VPP technique involves deposition of an oxidant species and exposure of the liquid oxidant to the vapor of a monomer. After the polymerization is completed (usually 5-60 min) the oxidant is washed away with an alcohol solvent and the conductive polymer thin film is left ready to be incorporated into an application. Not only has this technique overcome the insolubility of conductive polymers, the electrical and optical properties of the resultant conductive polymers have shown to be excellent compared to chemical and electrochemical synthesis techniques. [12,13] Due to these reasons, a large amount of VPP publications within the scientific literature have included electrochromic applications. [14,15] Researchers have extended the VPP technique with various patterning techniques such as inkjet printing, UV-patterning and more to create patterned electrochromic displays. [16,17] Recently, we have shown that using VPP combined with screen printing allows for PEDOT to be formed without incorporation of the polymer into the ink. [18] Instead, the oxidant species (an iron salt) is formulated into an ink and after deposition by screen printing, the oxidant is exposed to a monomer vapor, and after a washing step the VPP film is ready for use in displays, transistors, or other printed electronic Smart label technology such as indicators is a growing field due to society's demand for Internet of Things devices. New materials and technologies are continuously being discovered and developed in order to provide better resolution, better performance, or more environmentally friendly devices. Within this report, screen printing technology is combined with vapor phase polymerization to synthesize three conductive polymers; poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPy), and polythiophene (PTh). The conductive polymers are created in micrometer resolution and investigated for their electrochromic properties. PEDOT and PPy samples are combined into printed, la...

Screen Printed Reflective Electrochromic Displays for Paper and Other Opaque Substrates

“…The performance of the novel rOECD architecture presented herein was compared to that of the conventional OECD. − For this, OECDs of both reverse and conventional architectures with two layers of the S V4 PEDOT:PSS ink were used (referred to as Type B displays). Figure shows the typical current vs time plots, recorded during the ON switch, for the conventional and reverse OECD and their change in color (recorded with a photodiode as described in the Experimental Section) during switching.…”

All‐Printed Multilayers and Blends of Poly(dioxythiophene) Derivatives Patterned into Flexible Electrochromic Displays

“…However, the appearance of two peaks at 0.3 V indicates that the conducting polymer is not fully doped yet and thus might lack in electrical conductivity, in comparison to the conventional PEDOT. [13] The L*a*b* color space of the device in its oxidized and reduced states is included in Figure 2D, showing good color contrast values of ΔE* ≈20. This value, for a display not based on PEDOT:PSS, is considered good since other conductive polymers such as PPy-based all-printed displays have only reached a contrast value of ΔE* ≈17.…”

“…Additionally, the blends appear to be more transparent at lower positive voltages in comparison to the individual PProDOT-Me 2 film, which is related to the highly conducting nature of PEDOT. [13] The L*a*b* color space of the device in its oxidized and reduced states is also included in Figure 4D PEDOT:PSS-based devices used in commercial display products, thereby showing the great potential of this technology. Cyclic voltammetry of the PEDOT/PProDOT-Me 2 blend on FTO is shown in the supporting information (Figure S10).…”

“…Recently, we have shown that the VPP technique can be adapted for screen printing technology and that functional inks can be printed on the resultant conductive polymers for the fabrication of all-printed electrochromic devices, despite being based on insoluble conductive polymers such as polypyrrole (PPy) and polythiophene (PTh). [13] Within the recent report on combining VPP and screen printing, three conductive polymers, PEDOT, PPy, and PTh, were incorporated into all-printed, flexible electrochromic devices producing reflective displays that showed a light blue to dark blue, a grey to yellow, and a red to blue color change, respectively. [13] An alternative and interesting electrochromic conductive polymer is poly(dimethylpropylene-dioxythiophene) (PProDOT-Me 2 ).…”

“…[13] Within the recent report on combining VPP and screen printing, three conductive polymers, PEDOT, PPy, and PTh, were incorporated into all-printed, flexible electrochromic devices producing reflective displays that showed a light blue to dark blue, a grey to yellow, and a red to blue color change, respectively. [13] An alternative and interesting electrochromic conductive polymer is poly(dimethylpropylene-dioxythiophene) (PProDOT-Me 2 ).…”