Polyaniline as a Reversibly Switchable Electrochromic Material

摘要

Polyaniline is an interesting electrochromic material because its color can bechanged from clear to green, to blue, and to purple by electrochemical oxidation. The structural transformations associated with these color changes are shown in Scheme I. One of the possible applications for polyaniline is to use it as the active material in electrochromic windows. An electrochromic window is a multi-layered device (Scheme II) with the structure of a transparent rechargeable battery. A practical electrochromic window needs to have long color-cycling lifetime and good durability under solar radiation. This is a severe requirement because all layers of materials in Scheme II and interfaces between layers have to be durable under such electrochemical and photochemical stress. In this communication we report an initial study towards the construction of a polyaniline-based electrochromic window. We concerned ourselves with only half of the device shown in Scheme II, which consists polyaniline coated on tin oxide glass. We tested such a half-cell in an aqueous electrolyte to see if this part of the electrochromic device can be made durable enough for electrochromic applications and to find useful designing principles for constructing good devices.