Solar energy is steadily developing, requiring new materials and approaches to improve the efficiency of converting solar radiation into useful energy. In this context, selective absorbers capable of effectively capturing solar radiation and minimizing heat loss play a key role. One of the promising materials for creating such absorbers are thin films based on the AlCuFe alloy.
This alloy, having a quasi-crystalline structure, exhibits unique optical properties. The absence of periodicity in the arrangement of atoms leads to the formation of complex spectral characteristics that allow for the effective absorption of solar radiation in the visible and near infrared ranges, while simultaneously reflecting thermal radiation in the far infrared range.
AlCuFe films of different thicknesses were obtained using the ion-beam sputtering technique, with the substrates maintained at a temperature in the range of 480–490 °C. Analysis of the composition of the obtained films, carried out by the elastic recoil method, revealed the elemental ratio Al62Cu25Fe13. X-ray diffraction analysis of AlCuFe films with a thickness of about 200 nm showed the presence of both quasi-crystalline and crystalline phases in their structure.
To create selective absorbers, a method was used for depositing multilayer sandwich-type structures consisting of layers of Al2O3 (50 nm), AlCuFe (10–12 nm) and Al2O3 (70 nm) onto a copper film located on silicon wafers with an Al2O3 coating.
The measured solar radiation absorption coefficient for the obtained structures was 90%, while the thermal radiation coefficient in the near infrared region, measured at room temperature, was approximately equal to 2.5%. The paper also presents the results of measurements of the optical parameters and specific electrical resistance of the AlCuFe films.
Thin AlCuFe films deposited on a substrate can be optimized to achieve maximum selectivity. By varying the alloy composition, film thickness, and deposition parameters, it is possible to achieve high absorption capacity in the solar spectrum and low emissivity in the thermal range. This allows the creation of efficient solar collectors capable of capturing large amounts of solar energy and minimizing heat re-radiation losses.
The use of thin AlCuFe films as selective absorbers opens up new prospects for the development of solar energy, allowing the creation of more efficient and cost-effective devices for converting solar radiation into thermal and electrical energy. Further research in this area is aimed at optimizing the structure and parameters of films to achieve maximum efficiency and durability.
Author: T. Eisenhammer, A. Mahr, A. Haugeneder, W. Assmann
Institute: TiNOx Society of Energy and Energetics mbll, Schwere-Reiter-Strasse 35/26, D-80797 Munich, Germany, Ludwig Maximilian University of Munich, Department of Physics, Amalienstrasse 54, 80799 Munich, Germany, Department of Physics, Ludwig Maximilian University, Am Kulonwall, D-85748 Garching, Germany