Development and Fabrication of a Multi-Layer Planar Solar Light Absorber Achieving High Absorptivity and Ultra-Wideband Response from Visible Light to Infrared.

The objective of this study is to create a planar solar light absorber that exhibits exceptional absorption characteristics spanning from visible light to infrared across an ultra-wide spectral range. The eight layered structures of the absorber, from top to bottom, consisted of Al ₂ O ₃ , Ti, Al ₂ O ₃ , Ti, Al ₂ O ₃ , Ni, Al ₂ O ₃ , and Al. The COMSOL Multiphysics ^® simulation software (version 6.0) was utilized to construct the absorber model and perform simulation analyses. The first significant finding of this study is that as compared to absorbers featuring seven-layered structures (excluding the top Al ₂ O ₃ layer) or using TiO ₂ or SiO ₂ layers as substituted for Al ₂ O ₃ layer, the presence of the top Al ₂ O ₃ layer demonstrated superior anti-reflection properties. Another noteworthy finding was that the top Al ₂ O ₃ layer provided better impedance matching compared to scenarios where it was absent or replaced with TiO ₂ or SiO ₂ layers, enhancing the absorber's overall efficiency. Consequently, across the ultra-wideband spectrum spanning 350 to 1970 nm, the average absorptivity reached an impressive 96.76%. One significant novelty of this study was the utilization of various top-layer materials to assess the absorption and reflection spectra, along with the optical-impedance-matching properties of the designed absorber. Another notable contribution was the successful implementation of evaporation techniques for depositing and manufacturing this optimized absorber. A further innovation involved the use of transmission electron microscopy to observe the thickness of each deposition layer. Subsequently, the simulated and calculated absorption spectra of solar energy across the AM1.5 spectrum for both the designed and fabricated absorbers were compared, demonstrating a match between the measured and simulated results.