Nanoparticles give solar panels a green color

Details

Published on 14 May 2018

Researchers from AMOLF, the University of Amsterdam (UvA) and the Energy Research Centre of the Netherlands (ECN) have developed a technology to create efficient bright green colored solar panels, and ease large-scale application as building materials.

Photovoltaic research has much focused on maximizing the electricity yield obtained from solar panels: nowadays, commercial panels have a maximum conversion efficiency from sunlight into electricity of around 22%. To reach such high efficiency, silicon solar cells have been equipped with a textured surface with an antireflection layer to absorb as much light as possible. This creates a dark blue or black appearance of the solar panels.

To create the colored solar panels the researchers have used the effect of Mie scattering, the resonant backscattering of light with a particular color by nanoparticles. They integrated dense arrays of silicon nanocylinders with a diameter of 100 nm in the top module cover slide of a high-efficiency silicon heterojunction solar cell. Due to the resonant nature of the light scattering effect, only the green part of the spectrum is reflected; the other colors are fully coupled into the solar cell. The current generated by the mini solar panel (0,7 x 0,7 cm2) is only reduced by 10%.

The light scattering effect due to Mie resonances is easily controllable: by changing the size of the nanoparticles the wavelength of the resonant light scattering can be tuned, and the researchers are now working to realize solar cells in other colors: red panels can serve as roof tiles, white ones can serve as walls in buildings. And solar panels placed in nature are ideally green.

Reference

Verena Neder, Stefan L. Luxembourg, and Albert Polman, Efficient colored silicon solar modules using integrated resonant dielectric nanoscatterers, Appl. Phys. Lett. 111, 073902 (2017); https://doi.org/10.1063/1.4986796

From Photoniques special EOS issue, march-april 2018.