Multicolored electrochromism from benzodipyrrolidone-based ambipolar electrochromes at a fixed potential

Abstract

A series of ambipolar electrochromic (EC) materials composed of electron-withdrawing benzodipyrrolidone (BDP) moieties have been designed and synthesized. Upon incorporating different electron donors, various colors covering the whole visible range are achieved due to the different intramolecular charge transfer interactions in the BDPs. Interestingly, all the BDPs display dramatic color switching under negative potentials owing to their two-step reversible reductive processes. Consequently, multicolored electrochromism can be realized in the electrochromic devices (ECDs) based on the BDPs at different potentials due to their abundant redox states. Most importantly, by simply etching the ITO electrodes, reversible multicolored electrochromism can also be achieved in single-layered ECDs at a fixed potential owing to the ambipolar characteristics of the BDPs. This study may open up a new way for the utilization of ambipolar EC materials and the construction of multicolored ECDs.