Unique variable-gap polyheterocycles for high-contrast dual polymer electrochromic devices

We have carried out studies on an extensive series of electron rich monomers which oxidatively polymerize at low potentials. Alkyl derivatized poly(3,4-ethylenedioxythiophenes) (PEDOTʹs) exhibit a high degree of visible light transparency in the oxidized state, while being an opaque blue in the reduced state. These polymers can be switched rapidly (sub-second) between states with high optical contrasts of up to 60% AT. Multi-ring monomers have been prepared using EDOT moieties as terminal polymerizable unʹrts, to yield the most easily oxidized thiophene based monomers reported to date, which efficiently electropolymerize. Polymers have been prepared with electronic band gaps that range from a relatively low 1.4 eV up to 2.5 eV. The inclusion of transition metal ions, electronically coupled to the conjugated backbone, allows further tuning of the polymerʹs redox properties. These polymers behave as complementary electrochromic materials and have been employed in dual polymer electrochromic devices. Judicious choice of proper cathodically and anodically coloring polymers yield devices which exhibit high optical contrasts (>50% T), multi-color capabilities, long term switching stability (>104 deep switches), and rapid switching characteristics with 25% optical contrast observed with 100 mS switches.