Browsing by Author "Pohl, Felix"

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    Co-sputtering of A Thin Film Broadband Absorber Based on Self-Organized Plasmonic Cu Nanoparticles
    (Wiley-VCH Verlag, 2024-02) Drewes, Jonas; Perdana, Nanda; Rogall, Kevin; Hartig, Torge; Elis, Marie; Schürmann, Ulrich; Pohl, Felix; Abdelaziz, Moheb; Strunskus, Thomas; Kienle, Lorenz; Elbahri, Mady; Faupel, Franz; Rockstuhl, Carsten; Vahl, Alexander; Department of Chemistry and Materials Science; Nanochemistry and Nanoengineering; Kiel University; Karlsruhe Institute of Technology
    The efficient conversion of solar energy to heat is a prime challenge for solar thermal absorbers, and various material classes and device concepts are discussed. One exciting class of solar thermal absorbers are plasmonic broadband absorbers that rely on light absorption thanks to plasmonic resonances sustained in metallic nanoparticles. This work focuses on Cu/Al2O3 plasmonic absorbers, which consist of a thin film stack of a metallic Cu-mirror, a dielectric Al2O3 spacer, and an Al2O3/Cu-nanoparticle nanocomposite. This work explores two preparation routes for the Al2O3/Cu-nanoparticle nanocomposite, which rely on the self-organization of Cu nanoparticles from sputtered atoms, either in the gas phase (i.e., via gas aggregation source) or on the thin film surface (i.e., via simultaneous co-sputtering). While in either case, Cu-Al2O3-Al2O3/Cu absorbers with a low reflectivity over a broad wavelength regime are obtained, the simultaneous co-sputtering approach enabled better control over the film roughness and showed excellent agreement with dedicated simulations of the optical properties of the plasmonic absorber using a multi-scale modeling approach. Upon variation of the thickness and filling factor of the Al2O3/Cu nanocomposite layer, the optical properties of the plasmonic absorbers are tailored, reaching an integrated reflectance down to 0.17 (from 250 to 1600 nm).
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    A thin-film broadband perfect absorber based on plasmonic copper nanoparticles
    (Elsevier BV, 2022-08) Perdana, Nanda; Drewes, Jonas; Pohl, Felix; Vahl, Alexander; Strunskus, Thomas; Elbahri, Mady; Rockstuhl, Carsten; Faupel, Franz; Department of Chemistry and Materials Science; Nanochemistry and Nanoengineering; Karlsruhe Institute of Technology; Kiel University
    Increasing the efficiency of solar thermal collectors is extremely important as they are essential for many applications, ranging from the UV up to the NIR spectral range, from water heating systems up to micro-electromechanical systems. In this work, a plasmonic multilayer nanocomposite thin-film system that efficiently absorbs solar radiation across an extended spectral range was simulated and experimentally tested. Novel to our approach, copper nanoparticles in an alumina matrix were chosen as the nanocomposite material. Compared to other plasmonic materials such as gold or silver, copper is more abundant and economic. The alumina matrix provides high thermal stability, good optical properties, and corrosion protection. Using a multiscale-modeling approach, we inspect on computational grounds the effect of the nanoparticle filling factor, the angle of incidence, and the thin-film thicknesses on the absorber performance. We found that an optimally designed device absorbs up to 90% light energy from 200 nm to 1800 nm. To validate the simulations, two promising absorber layouts are experimentally realized. Their performance compares very well with simulations.