Superabsorbers nanomaterials that trap sunlight

ICMAB researchers have designed ultrathin materials that maximize the absorption of light in a large range of the solar spectrum. The followed strategy is low cost and fully scalable. The obtained superabsorbers materials have many potential applications, especially in the field of photovoltaic energy and photodetection.

Coloured Scanning Electron Microscopy (SEM) image of the germanium photonic structure fabricated over a gold layer (ICMAB)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 Institute of Materials Science of Barcelona (ICMAB-CSIC), 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.

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.