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Dale Karas1 Astrid Miller1 Jongmin Byun1 Jaeyun Moon1

1, University of Nevada, Las Vegas, Las Vegas, Nevada, United States

To achieve effective solar power generation with photovoltaic arrays and concentrated solar power technologies alike, specialized material coatings are essential for the system-wide control of propagating radiation – specifically for solar-thermal power conversion, a class of high-temperature, air-stable material coatings, characterized by high UV-VIS absorptance and low NIR emittance are favorable for energy efficient operation, functioning to mitigate losses via re-radiated waste heat. The synthesis of intrinsic coatings, as opposed to the use of multilayer heterogeneous configurations, generally offer the benefit of easier fabrication at the cost of slightly reduced absorptive performance. We report on coatings fabricated through hydrothermal and co-precipitation nanomaterial syntheses, in which uni-metallic and bi-metallic oxides (CuO, Co3O4, Cu0.15Co2.84O4, and Cu1.5Mn1.5O4) are synthesized as nanomaterials before being ported to an absorber coating; these reaction methods consistently generate phase-stable products that are viable for bulk manufacturability. To maximize the spectral absorptance capability of the coatings, surface texturing modifications are introduced by embedding sacrificial polymer beads in the coating precursors prior to high-temperature curing and annealing reaction stages. In optimizing the reaction conditions and ensuring best absorptance capability, nanoparticle features are analyzed during various synthesis stages via optical and field-emission scanning electron microscopy data. In scanning for morphological detail in both the spatial and frequency domain, multiresolution analysis is used to approximate particle density, sizing, and distribution. This data is then correlated to the materials’ scattering events using a first-order Harvey-Shack model and differential raytracing methods, which approximate scatter contributions to the spectral irradiance profile of the material, relating surface structuring to the coating’s solar absorptance. Additional performance enhancements are implemented for reducing waste byproducts and minimizing water consumption, to ensure the low-cost of process reactants and ease-of-synthesis for high-purity materials. In this way, coupled simulation and experimental approaches for characterizing preceding nanomaterial syntheses result in absorber coatings tenable for long-term usage in solar power generation systems.

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