Application of high refractive index and/or chromogenic layers to control solar and thermal radiations

Motofumi Suzuki; Kensuke Nishiura; Shoma Masunaka; Naoto Muroi; Kyoko Namura

doi:10.1117/12.2237410

26 September 2016 Application of high refractive index and/or chromogenic layers to control solar and thermal radiations

Motofumi Suzuki, Kensuke Nishiura, Shoma Masunaka, Naoto Muroi, Kyoko Namura

Author Affiliations +

Proceedings Volume 9929, Nanostructured Thin Films IX; 99290G (2016) https://doi.org/10.1117/12.2237410
Event: SPIE Nanoscience + Engineering, 2016, San Diego, California, United States

Abstract

In this presentation, we demonstrate that high refractive index materials such as β-FeSi₂ and/or chromogenic materials such as VO₂ are the key to control solar and thermal radiations. β-FeSi₂ is known as an eco-friendly semiconductor and for sputtered polycrystalline β-FeSi² thin films, we recently found that λ~0.3 in IR region, while n is higher than 5. On the other hand, another interesting optical property of β-FeSi₂ is that both n and k are considerably high in visible to NIR region ( λ ≤ 1.55 μm). Using these optical properties in IR and VIS, we designed multilayers consisting of β-FeSi₂/SiO₂/β-FeSi₂/W, where the upper β-FeSi₂ layer absorbs VIS and NIR (λ ≤ 1.0 μm) and the bottom β-FeSi₂ layer/W absorbs IR (1.0 ≤ λ ≤2.0 μm). The optimized multilayers absorb more than 90% of solar energy and the eminence at 450 °C is lower than 10%. The perfect absorbers with high refractive index layers are useful for applications to solar selective absorbers for solar thermal power generation and spectrally selective thermal emitters for thermophotovoltaic power generation, IR heaters, radiation cooling. Replacing one of β-FeSi₂ layers with a chromogenic material allows active control of solar and thermal radiation. In the presentation, we also demonstrate the active perfect absorbers including a VO₂ layer in NIR region.

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Motofumi Suzuki, Kensuke Nishiura, Shoma Masunaka, Naoto Muroi, and Kyoko Namura "Application of high refractive index and/or chromogenic layers to control solar and thermal radiations", Proc. SPIE 9929, Nanostructured Thin Films IX, 99290G (26 September 2016); https://doi.org/10.1117/12.2237410

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