What are they?
Silicon-sapphire nanopatterns have been developed for photovoltaic modules that scatter green light towards the onlooker, and thus better integrate the panels into their built environment. The dielectric scatterers were created ‘through soft-imprint lithography, which works like an optical rubber stamp to imprint a dense array of silicon nanocylinders onto the cell surfaces. Each cylinder is about 100nm wide and exhibits an electromagnetic resonance that scatters a particular wavelength of light,’ the researchers state in the accompanying research paper.
Who is involved?
Authors Verena Neder, Institute of Physics, University of Amsterdam, Stefan Luxembourg, ECN Solar Energy, and Albert Polman, Centre for Nanophotonics, published their paper Efficient coloured silicon solar modules using integrated resonant dielectric nanoscatterers in the journal Applied Physics Letters (find it here: http://bit.ly/2f9mNr7).
How can they be used?
While research normally focuses on improving the efficiency of the panels and reducing production costs, Neder et al focused on making the design of the panels more attractive to potential users, as their obvious visibility might deter people from installing solar panels on the roof of their house. Nevertheless, the dielectric Mie nanoscatterers lose 10% of their power compared to non-coloured panels.
How are they novel?
This is not the first time that the production of coloured solar panels has been examined, but so far, the dye and reflective coatings, which produce the colour, have reduced the efficiency of the panels too much. The nanopatterns could also be useful in making solar cells more efficient by stacking numerous layers that each absorb different parts of the light spectrum. According to the researchers, this could boost efficiency to use 30% of the sun’s light to create energy (as opposed to current values of around 20% absorption). Next, the researchers are designing imprints to create red and blue solar cells, but the real challenge is white. ‘You have to combine different nanoparticles, and if they get very close to each other they can interact and that will affect the colour,’ Polman said. ‘Going to white is a really big step.’