Silver grid electrodes for faster switching ITO free electrochromic devices

Low-cost electrochromic devices presenting fast switching continue to have an enormous interest for industrial applications; however the durability of the devices is a parameter of critical importance. The present work describes the preparation and characterization of ITO free electrochromic devices, being the use of hybrid electrodes for low-cost electrochromic devices the main focus. It was used silver grids (silver ink) as electrically conductive electrodes. These grids were screen-printed on polyethylene terephthalate (PET), using two different patterns and different line widths. The printing of a conductive polymer film on top of the grids for electrochemical protection of the metal was evaluated. These grids were characterized in terms of equivalent resistance and light transmission, considering each pattern, as well as electrochemical stability. The resulting electrochromic devices were tested using cyclic voltammetry, spectroelectrochemistry and colorimetry. The durability of the devices was characterized through the analysis of color contrast over time during continuous operation conditions using a cycling program. These experiments displayed electrochromic devices performing 100 cycles before degradation with switching times of 4.5 s and a color contrast (Delta E) of 27 or a variation in transmittance of 50% between redox states. (C) 2016 Elsevier B.V. All rights reserved.