Synthesis of a perylenediimide-viologen dyad (PDI-2V) and its electrochromism in a layer-by-layer self-assembled multilayer film with PEDOT:PSS

A new electrochromic molecule, perylenediimide-viologen dyad (PDI-2V), was synthesized and used in the fabrication of layer-by-layer (LBL) self-assembled multilayer films with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). Since PDI-2V is a tetracationic organic molecule with high molecular weight, it showed strong electrostatic adhesion to negatively charged PEDOT: PSS. When the electrochromic behaviour of the resulting LBL film was investigated with a single type electrochromic device, the PDI-2V showed a three-stage color change from red to blue to violet under the reduction potential range. A dual type electrochromic device was also fabricated with P3HT spin-coated ITO as a counter electrode. This device exhibited a sharp color change between deep red and dark blue when the applied potential was switched from +2.0 V to -2.0 V.