Ink-jet printing for the fabrication of a flexible electrochromic device based on the water-soluble viologen-functionalized dendrimer

Abstract

This paper reports the preparation of an ink-jet printed flexible electrochromic device based on a water-soluble viologen-functionalized dendrimer. Polyamidoamine (PAMAM) dendrimers were modified with different concentrations of 1-1 bis(propylamine)-4,4'-bipyridylium dibromides to obtain solution-processable electrochromic materials (K1/2 and K1 ). FTIR, NMR, and elemental analyses are used to characterize synthesized viologens. Moreover, their electrochemical properties were investigated using cyclic voltammetry in an electrolyte solution consisting of 0.1 M HCl to find the optimum viologens. The low-cost ink-jet printer was used to print the prepared water-soluble electrochromic inks onto the ITO coated PET substrate to form desired transparent patterns. The electrolyte was applied on the printed electrochromic ink to make a sandwich with another ITO coated PET to prepare the electrochromic devices (ECD). By applying an electrical potential (0 to-2 V), the transparent ECD’s color changed from colorless to blue. The color changes for the optimum ECD (K1 ), which had more viologen units on the dendrimer, was accompanied by an optical contrast of 47% and 311.5 cm C col-oration efficiency at 600 nm.2-1.