With hopes of exploring deeper and deeper into space, creating a “constellation of satellites” for navigation to Internet service, and even distributing solar power collected from space directly to Earth (space-based solar power), we will need new solar cell designs to more efficiently power future endeavours in the final frontier.

Figure 1. An illustration of solar panels used in higher orbit space for space-based solar power [1].

My research, based in the Space Photovoltaics group and spearheaded by Prof. Louise Hirst in the Cavendish Laboratory, focuses on ultra-thin nanowire solar cells. Nanowires are just like normal electrical wires other than the fact that they are extremely small – just about the length scale of a virus. Like conventional wires, nanowires can be made from a variety of conducting and semiconducting materials like copper, silver, gold, iron, silicon, and carbon. In fact, these particularly promising nanowire solar cells utilise gallium arsenide and indium phosphide from a class of materials known as III-V semiconducting materials, which are the same materials commonly found in LEDs and computers.


These extremely thin solar cells are cheaper to send to space as they are more lightweight and use less material compared to the current state-of-the-art solar cells. Less material usage also enables more sustainable production. Furthermore, at these ultra-thin geometries of less than a thousandth of a millimetre, nanowire solar cells are quicker at extracting electrons through the material while being flexible enough to integrate into spacecraft systems. Recently, the group has shown that ultra-thin solar cells have an intrinsic tolerance to particle radiation and can withstand the harsh environments in outer space, which would especially enable longer spacecraft and satellite lifetimes as we explore distant, unexplored areas of the universe [2].


While the ultra-thin nanowire solar cells offer a lot of promising advantages, making something that thin also makes it much easier for sunlight to escape out of solar cells and thus potentially producing less electricity. However, by physically optimising the design and integration of nanowire “forests”, the nanowires can act as pillars of an optical grating and trap sunlight within the solar cell for longer – increasing absorption and maximizing efficiency. Because of the larger surface area of nanowires compared to a planar geometry, another avenue of my research looks at different treatments on the solar cells to make the surface less reactive and less likely to induce defects in these high radiation environments, improving the electron extraction efficiency.

Using a combination of simulations and experimentation, I hope to further optimise and eventually fabricate nanowire solar cell designs for space photovoltaics, enabling rapid development of satellites and spacecrafts for a more connected Earth.

References:

  1. Oberhaus, Daniel. “Space Solar Power: An Extraterrestrial Energy Resource For The U.S.” Innovation Frontier Project. 18 August 2021. https://innovationfrontier.org/space-solar-power-an-extraterrestrial-energy-resource-for-the-u-s/
  2. Sayre, Larkin et al. “Ultra-thin photovoltaics for radiation-tolerant space power systems.” Proceedings SPIE. (2021) https://doi.org/10.1117/12.2583519

Anish Chaluvadi

NanoDTC PhD Student, c2021