As of September 2018, it has been estimated that 11 million American homes have been powered by solar energy, amounting to a total installed solar photovoltaic (PV) capacity of 58.3 gigawatts (GW)1. As the global interest in alternative energy continues to rise, researchers have continued to investigate different ways to improve the efficiency of converting solar energy into an electrical voltage. To this end, various advances have incorporated nanotechnology into solar panels to simultaneously improve efficiency while also reducing associated manufacturing and installation costs. Despite this promise, various challenges still exist in manufacturing nano-based solar panels as a result of the current limitations in manufacturing nanomaterials at an industrial scale.
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Advantages of Nanostructured Solar Cells
One of the biggest disadvantages of solar energy is the high cost associated with manufacturing solar cells, especially when compared to the cost of utilizing coal and gas for energy. Furthermore, modern solar cells can lose as much as 10% of acquired power as a result of direct optical loses, since the surface of these cells will reflect anywhere between 2% - 10% of incoming sunlight. Nanotechnology offers the ability to solve this problem3.
Since nanostructures typically are only a few hundred nanometers in size, they create an interface between the air and the nanostructure, particularly those comprised of silicon, become graded rather than planar. This change in the solar cells’ design allows for light to be precisely guided and absorbed into the cell, rather than reflected away.
Silicon Nanoparticles Enhance Solar Cells
Silicon nanoparticles exhibit many useful properties, some of which include an active surface state, low bulk density as well as unique photoluminescent and biocompatible properties. As a result, these nanoparticles are often incorporated into lithium-ion batteries, solar energy cells, micro, and integrated semiconductors and luminescent display devices2. When applied for solar power products, the size and microstructure of silicon nanoparticles, as well as their luminescence and quantum efficiency properties are highly specific.
A recent study conducted in Russia investigated a novel technological process for the production of nanosilicon films that could be applied to solar cells. This process involves synthesizing solid silicon oxide (SiO) monoxide, following by disproportionation of solid SiO following heat treatment of the material. Finally, the silicon nanoparticles were separated from the products that resulted from the heat treatment of SiO4. As a result of these processes, the extremely fine silicon particles remained bound to the SiO matrix until they were removed by etching the particles into a hydrofluoric acid solution. Not only did this technique ensure that the particle dimensions remained within the 2 to 10 nanometer (nm) range, but it also provided good antireflective and passivation properties without compromising the purity of the final product. As a result, the manufacturing process developed in this study produced nanosilicon that is optimal for solar cells applications4.
Advancements in Nanosilicon Solar Cells
As research has continued to support the incorporation of nanotechnology and solar technology, the use of resonant colloidal nanoparticles has been shown to improve the performance of halide perovskite solar cells that are derived from organometals. Furthermore, resonant metallic nanoparticles, when incorporated into these solar cells, have successfully increased light absorption and charge separation to ultimately improve the efficiency of applied solar panels. To avoid the potential reactivity of the metallic nanoparticles with the perovskite halides, a recent study applied photocurrent and fill-factor enhancements to organometal halide perovskite solar cells that also contain resonant silicon nanoparticles between its active layers. This study found that the overall efficiency of the solar cells improved by as much as 18.8%, whereas fill factor, which is a parameter that determines the maximum power that can be obtained from the solar cell, increased by a staggering 79%5.
- “U.S. Solar Market Insight” – Solar Energy Industries Association
- “Silicon (Si) Nanoparticles – Properties, Applications”
- “Nanostructured Solar Cells” – DTU Nanotech
- Gribov, B. G., Zinov’ev, K. V., Kalashnik, O. N., Gerasimenko, N. N., Smirnov, V. N., et al. (2017). Production of Silicon Nanoparticles for Use in Solar Cells. Semiconductors 51(13); 1675-1680. DOI: 10.1134/S1063782617130085.
- Furasova, A. D., Calabro, E., Lamanna, E., Tiguntseva, E. Y., Ushakova, E., et al. (2018). Resonant Silicon Nanoparticles for enhanced Light Harvesting in Halide Perovskite Solar Cells. Applied Physics. DOI: 10.1088/1742-6596/1092/1/012038.