High-temperature solar-thermal conversion by semiconducting β-FeSi2 absorbers with thermally stabilized silver layers
| Autor: | Kazuto Noritake, Takeharu Kato, Masasuke Takata, Takuhito Tsutsui, Daisaku Yokoe, Yoshiki Okuhara, Tomohiro Kuroyama |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Materials science Renewable Energy Sustainability and the Environment Band gap business.industry Infrared Energy conversion efficiency Analytical chemistry 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Low emissivity Optics 0103 physical sciences Absorptance Emissivity 0210 nano-technology business Absorption (electromagnetic radiation) Refractive index |
| Zdroj: | Solar Energy Materials and Solar Cells. 174:351-358 |
| ISSN: | 0927-0248 |
| Popis: | In-situ high-temperature measurements of optical constants (refractive indices n and extinction coefficients k) for each layer of solar selective absorbing multilayers were carried out to simulate solar-thermal conversion efficiency at high temperatures. Conventional Mo layers showed a significant rise in infrared emissivity and a degradation of selective absorbing behavior with the increasing temperature. In contrast, thermally stabilized Ag layers maintained low emissivity even at temperatures below 700 °C. In these layers, agglomeration and vaporization were suppressed by SiNx nano-particles dispersed in the Ag matrix and interfacial W adhesive layers, respectively. The interband absorption of β-FeSi2 layers at higher temperatures revealed that larger n and k in the infrared region due to thermally excited electrons induced no rise in emissivity of the multilayers, and the narrower band gap based on Einstein's model shifted the absorptance cut-off wavelength closer to the ideal value and hence resulted in a higher solar absorptance. The solar-thermal conversion efficiencies of the multilayers consisting of low emissivity Ag layers with β-FeSi2 absorbers were found to be greater than 75.9%, as estimated from the temperature dependence of n and k spectra. |
| Databáze: | OpenAIRE |
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