“Our findings are a significant conceptual advance in our understanding of light-matter interaction, and may likely inspire novel designs in photonic-enhanced photovoltaics, photo-detection, bio-sensing, atomic cooling and many other opto-electronic applications”Christian Schuster
Researchers from the University of York in partnership with NOVA University Lisbon have developed a new design for photovoltaic (PV) solar cells that improves their ability to absorb light by 125% in a key enhancement to optical-enhanced solar energy. The concept, based on a checkerboard pattern, could bring greater use of renewable energy through thinner, lighter and more flexible solar panel arrays in biosensing applications, atomic cooling, acoustic noise shields, and even fixed to roof tiles, boat sails and camping equipment.
Before coming up with checkerboard lines, the team examined the pentagon and its low symmetric properties, and how it is used in nature to optimize stability and growth, as well as its role in nanowires and carbon nanotubes. However, as shown in Optica [Li et al. Optica (2020) DOI: 10.1364/OPTICA.394885], they realized the pentagon shape might not be necessary if the grating lines were modulated, with the simplest modulation being the checkerboard pattern, defined here by its grating period, etching depth and photonic domain size.
The team demonstrated how these simple grating lines could perform as well as existing light-trapping designs, using a shallow and periodic grating as the basic element of a quasi-random structure, one that is highly suitable for industrial mass production. This approach boosted the absorption of slim solar cells and improved on surface design over silicon in solar cells, which is extremely energy-intensive to make.
The approach offers similar absorption enhancement of more sophisticated designs but brings more light deep in the plane and less light near the surface structure itself. Although thinner material layers absorb less sunlight, the majority of the near-infrared light would pass through a thin silicon layer as if it were a transparent sheet of glass.
To improve on the generative ability of existing PV, the use of optics to manipulate light within solar cells means it can be better channeled towards such materials. This prevents the escape of light outwards, quickly trapping it inside the cells, ensuring it is fully converted into electricity.
The work allows for the expansion of photovoltaics with a much reduced carbon footprint, and would be cheaper than existing methods as well as reducing our dependence on refining the silicon raw material. As Christian Schuster said “Our findings are a significant conceptual advance in our understanding of light-matter interaction, and may likely inspire novel designs in photonic-enhanced photovoltaics, photo-detection, bio-sensing, atomic cooling and many other opto-electronic applications”.
The checkerboard pattern also allows quick turnaround from design to implementation and potential modifications, while its simplicity, reduced surface area and higher robustness to imperfections offers many benefits.
Checkerboard pattern improves on PV solar cell efficiency. Credit: Davide Zecca (davidezecca.artstation.com)