Electrochromic properties as a function of electrolyte on the performance of electrochromic devices consisting of a single-layer polymer

Abstract

Herein, a study on varying salts and their composition used in the gel electrolyte for a one-step lamination assembly procedure for electrochromic devices was carried out to explore their effects on various electrochromic performance parameters, such as color uniformity, photopic contrast, switching speed, and optical memory. Electrochromic polymers formed in different gel electrolyte compositions are highly dependent on the type, amount, and composition of salt used. The following groups of salts were investigated: ionic liquids, ammonium salts, and lithium salts. The lithium salts yielded devices with the best color uniformity, photopic contrast as high as 48%, and switching response speeds as low as 1s for 5.5cm2 devices using the electroactive monomer 2,2-dimethyl-3,4-propylenedioxythiophene (ProDOT-Me2) to generate the electrochromic polymer. Hermetically sealed electrochromic devices exhibited optical memory of 27h for a 2% photopic transmittance loss under normal laboratory conditions, and a 171cm2 electrochromic device was demonstrated.