Self-Assembly of Light Harvesting Films Using Functional Solvents

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This Discovery program will explore a new methodology using bio-based solvents to make ordered polymer nanostructures suitable for light harvesting using gas-expanded liquids (GXL). A renaissance is underway for additive manufacturing, such as 3D printing and rapid prototyping. However, current approaches are far too slow and do not provide the high performance material properties required for emerging applications in light/energy harvesting. For these high performance light harvesting coatings and devices, including photovoltaic encapsulants and anodes, photocatalytic coatings and greenhouse films; new nanoparticles (NPs) using earth abundant and friendly elements and a new way to control their assembly into ordered structures is required. Currently, multi-step complex chemistries are required to form NPs, stabilize them, then attach them to surfaces to form 3D ordered structures, with a poor ability to control surface topology. In these approaches, a solvent is normally required in the various reaction/processing steps to facilitate NP dispersion and deposition. However, current solvents are considered VOCs, which are becoming increasingly regulated for industrial use, while also they provide no functionality and give very poor control of the NP self-assembly process and deposition. *** Our unique research program will examine how green bio-based solvents including alkyl acetates, carbonates and lactates can be used to control both the polymer/NP reaction chemistry and deposition steps to enhance the end-use structure and performance. For NP growth, we will explore how sol-gel chemistry can be used to grow a variety of metal alkoxide building blocks in an oriented fashion, both in solution or from various 2D surfaces such as graphene sheets. This will entail examining the physical chemistry of how the functional solvents co-ordinate to and stabilize these growing NPs and polymer-NP assemblies, and how various metal dopants or quantum-dot nanocrystals can be integrated into the growing molecular framework. Density functional theory (DFT) modeling will be used to understand the growth and assembly process as a function of solvent stability, while being used to predict dopant/NP integration. Fabrication of these building blocks into films and coatings will be explored, where the materials performance and oriented surface topology's can control sunlight for next-generation light harvesting coatings using 3D fabrication/printing. By controlling the UV curing and solvent/solute interactions during fabrication, we can design appropriate structures and surface topologies using these next generation materials. The resulting films and devices will be characterized for light conversion and electron transport effects by various physico-chemical techniques and synchotron studies at the Canadian Light Source, while DFT will be used to examine their energy-transfer processes. **