Nanostructures on Solar Cells Boost Power Conversion Efficiency

The photovoltaic (PV) industry is booming, driven by the increasing need for clean energy and decreasing costs. Researchers are constantly developing materials and light management techniques to improve the power conversion efficiency of solar panels. They are exploring several approaches to boost efficiencies, such as tandem cells, perovskite materials, and artificial intelligence to optimize the design and fabrication of solar cells.

Among these techniques, light management methods are attracting much research attention as they push solar cells closer to their theoretical maximum efficiencies. While some materials may offer the potential for higher efficiency, they can be expensive or complex to produce. Light trapping methods provide a way to boost the performance of existing, well-understood materials in a potentially more cost-effective manner.

 

PV panel catching the sun rays. Image used courtesy of Adobe Stock

 

Nanostructures like pyramids, cones, or wires work like tiny "light traps." They reduce the reflection of sunlight, causing light to bounce around inside the structure instead of escaping, thus increasing the chances of the light being absorbed and converted into electricity. Furthermore, they significantly increase the effective surface area of the photovoltaic cell. By carefully tuning the size and shape of nanostructures, researchers can make solar cells more effective at absorbing different wavelengths of light. In other words, the structures can also extend the range of the solar spectrum the cell can use, leading to overall better performance.

Researchers from Abdullah Gül University, Turkey, suggest that depositing tiny hemispheres on the surface of solar panels can boost their efficiency by up to two-thirds as they capture light from a wider angle.

 

Enhancing Sunlight Absorption Through Bumps

The researchers studied photovoltaic cells made of organic polymer P3HT: ICBA as the active layer with an aluminum layer beneath it. The flexible Poly (methyl methacrylate) or PMMA layer acts as the substrate with an additional transparent protective layer of indium tin oxide (ITO). They tested different nanostructure shapes on the surface of this structure and found spherical nanoshells trap and circulate light most effectively. For analysis of various nanostructures, they carried out 3D finite element analysis (FEA) and used transverse electric or transverse magnetic fields to simulate light sources.

 

Illustration of the proposed solar cell structure. Image used courtesy of SPIE

 

From FEA analysis, the team found the bumps showed 36% and 66% improvements in light absorption, depending on the polarization of the light, by providing an angular coverage of up to 82 degrees. The researchers did not build physical versions of the solar cells based on this concept, but they are confident if the principle works, new photovoltaics can be beneficial in various application areas of organic solar cells, such as biomedical devices and applications like power-generation windows and greenhouses, Internet of Things, and more.