Pigments of My Imagination: Controlling Color and Redox Properties in Conjugated Organic Electrochromic Materials

The properties of 3,4-dioxythiophene (DOT)-based π-conjugated electrochromic polymers (ECPs) and molecules are explored with a focus on controlling structure-property relationships to achieve desired light absorption across the visible region of the spectrum. Because of the electron rich nature of the DOT moieties, the cathodic polymers can switch to highly transmissive oxidized states, while UV absorbing anodic systems can still be effectively oxidized, giving these DOT materials the potential to be utilized in full color window or non-emissive display applications in either approach. This work has an emphasis on comparing these two approaches. The use of a dialkylthiophenme monomer is explored as an electron rich monomer that maintains a wide optical gap and increases redox stability. This principle is extended into random all donor polymers to create broadly absorbing polymers with low oxidation potentials and improved optical memory. This work delves into anodically coloring materials as an alternative method for high contrast in electrochromic materials. Conjugation broken polymers are synthesized and utilized to this effect but lead to poorly switching materials. This failure leads to fundamental analysis of how color is controlled in anodically coloring molecular systems where the radical cation state is being directly manipulated thorough the design of the molecular structure. Finally, this work culminates with new design rules for the next generation of conjugated organic electrochromic materials.Ph.D