One of the challenges in the field of photovoltaic energy is to maximize the sunlight absorbed using the minimum quantity of material, in order to maximize its efficiency.
Researchers from ICMAB, led by Dr. Agustín Mihi, have created materials that largely absorb a wide range of the solar spectrum, between 400 and 1500 nm, using an ultrathin layer of less than 100 nm thick of material.
The followed strategy combines thin layers of semiconductors on a metal support (in this case, germanium on gold), to maximize the absorption in the visible range (400-700 nm), and the nanostructuring through nanolithography of the germanium layer in a square matrix, so that it acquires plasmonic and photonic properties, and maximizes the absorption in the near-infrared area (700-1500 nm).
The procedure to synthesize this photonic structure is completely scalable, which adds interest to the aforementioned advantageous optical properties. Moreover, the researchers provide, in the study published in Advanced Materials, the design guidelines to synthesize other types of materials following the same strategy.
The resulting superabsorber material has a great potential in applications in which a large quantity of light is wanted to convert into electrons, such as photodetection, photocatalysis, and in the field of photovoltaic energy to obtain electrical energy. We are heading for a future with thinner and more efficient solar panels!
Figure: a) Coloured Scanning Electron Microscopy (SEM) image of the germanium photonic structure fabricated over a gold layer; b) (left axis) Solar spectral irradiance that reaches the sea level (yellow) with the fraction absorbed by our architecture (Orange) and the total absorption of our superabsorber (right axis).
Reference article: Ultrathin Semiconductor Superabsorbers from the Visible to the Near-Infrared. Pau Molet, Juan Luis Garcia-Pomar, Cristiano Matricardi, Miquel Garriga, Maria Isabel Alonso and Agustín Mihi. Advanced Materials, 12 January 2018. DOI: 10.1002/adma.201705876.
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UPDATE: This news appeared in La Vanguardia: read it here.