All Polymer Electrochromic Matrix Display

Emerging see-through display (i.e., transparent display) display is significant in future sophisticated displays such as wearable and portable electronics, augmented and virtual reality, electronic papers/billboards, digitized shopping displays, head-up display, and other new-generation displays. The non-emissive electrochromic (EC) materials and devices have received remarkable attention for use in the display electronics, due to the advantages such as their excellent outdoor readability, low power consumption, wide-viewing angle, and eye-saving features. However, optical signal crosstalk between multi-pixels in matrix display is serious problem, which originated from the unwanted charge transfer in EC components. In addition, the widely used inorganic-based transparent conducting electrodes (e.g., indium thin oxide and fluorine doped tin oxide) suffer from issues such as poor mechanical flexibility and an energetic mismatch between the organic-inorganic semiconductor interface. Thus, reduction of the signal crosstalk is a key factor related to the successful fabrication of matrix EC displays. In this research, we have successfully demonstrated a photolithographic patterning of all-polymeric EC components like matrix electrode, ion storage layer, solid-state electrolyte, and EC active materials. Highly capacitive and conductive conjugated polymers were used as matrix electrodes lines for passive matrix-based display operation. The transparent conductors exhibited low sheet resistance and high transmittance, which leads to fabrication of transmissive matrix displays. Great reduction of the crosstalk was shown by using the direct isolation of highly wettable and crosslinkable electrolyte thin film in high resolution <i>in-situ</i> photolithography. Ionic liquid based poly(ethylene glycol) diacrylate precursor solutions can be easily wettable on the ionic storage layers, plastic substrates, and EC polymers due to absence of polar solvent and addition of thiol based monomers. The whole polymer, patterned EC display pixels exhibited transparent/flexible display application with very low power consumption by an electrochemical behavior of the EC polymers in low voltage and their enlarged optical memory by robust electrical double layer in ionic liquid. A subtractive color can be actively tuned in matrix display, along with the laterally stacked subpixels based on micro-patterned EC polymers which have no interference with each other. These findings represent a novel strategy for fabricating flexible, dynamically color-tunable EC displays and are expected to advance the development of future see-through display applications.