Printable All‐Organic Electrochromic Active‐Matrix Displays

TLDR

All‑organic active‑matrix displays based on electrochemical smart pixels on flexible substrates are reported, combining low‑voltage electrochemical transistors with electrochromic cells for robust, low‑voltage operation. The study aims to develop a robust, easily manufacturable display technology by evaluating electrochromic polymers for high color‑switch contrast and minimizing material complexity. The display uses PEDOT:PSS as active material and conducting lines, integrating a three‑terminal electrochemical transistor with an electrochromic cell and an additional PEDOT:PSS layer on the counter electrode, evaluated with various polymer materials. The authors achieved a 65 % fill factor and a five‑step manufacturing process enabling roll‑to‑roll production on paper or plastic substrates.

Abstract

Abstract All‐organic active matrix addressed displays based on electrochemical smart pixels made on flexible substrates are reported. Each individual smart pixel device combines an electrochemical transistor with an electrochromic display cell, thus resulting in a low‐voltage operating and robust display technology. Poly(3,4‐ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonate) (PSS) served as the active material in the electrochemical smart pixels, as well as the conducting lines, of the monolithically integrated active‐matrix display. Different active‐matrix display addressing schemes have been investigated and a matrix display fill factor of 65 % was reached. This is achieved by combining a three‐terminal electrochemical transistor with an electrochromic display cell architecture, in which an additional layer of PEDOT:PSS was placed on top of the display cell counter electrode. In addition, we have evaluated different kinds of electrochromic polymer materials aiming at reaching a high color switch contrast. This work has been carried out in the light of achieving a robust display technology that is easily manufactured using a standard label printing press, which forced us to use the fewest different materials as well as avoiding exotic and complex device architectures. Together, this yields a manufacturing process of only five discrete patterning steps, which in turn promise for that the active matrix addressed displays can be manufactured on paper or plastic substrates in a roll‐to‐roll production procedure.