Center for Functional Nanomaterials Seminar

The precursor method is one solution to the issues associated with many conjugated polymers (CPs), namely processability and solubility. Processability is requisite for the utility of these polymers as electrochromics, conductors, in organic photovoltaics or for any of the myriad applications of CPs. The precursors are prepared either via condensation polymerization of an electroactive moiety with a silane (Main Chain) or via attachment of the aromatic monomer as a pendant group on a polymerizable norbornene unit (Side Chain). Precursor materials can be patterned and then oxidatively (chemically or electrochemically) converted to a conjugated, electrochromic species. This is accomplished either by the crosslinking of electroactive pendant units or through electrochemical desilylation and aromatic-aromatic coupling. The materials prepared in this way are color matched to those using electrodeposition with the same base chromophore.
Using these precursors, it is possible to prepare electrochromics inside assembled solid-state devices. The same polymeric material can be made through in situ conversion (oxidation inside an assembled device) as via solution methods (ex situ conversion via electrochemical or chemical oxidation), saving a step in device preparation. Clean substrates were not needed for this method, removing another step in device production. In addition, other novel processing methods for the precursor technology include the use of aqueous electrolytes for the conversion process, enabling greener technology as well as potentially extending the use of our system to biological applications. A new device architecture for electrochromic fabric has been designed and used with the precursor method, as well. Color changing textile could lead to chameleonic fabric, as well as low-energy consumption flexible, wearable displays. We have used PEDOT-PSS impregnated spandex to build and study electrochromic devices.