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Is solar wallpaper on the way thanks to graphene nanotechnology?

Posted by Alex Barrett on 18 April 2016 at 10:20 am

What if we could put solar panels everywhere in the form of solar wallpaper?

At the moment installing solar photovoltaics (Solar PV) requires carefully positioning the solar panels to get as much sunlight as possible. Tracking systems can be set up so that the panels follow the path of the sun, producing the maximum energy all day long. When installing a solar PV system we have to carefully consider the angle of our roof, and how much sunlight it is likely to get. However this might not always be the case. Suppose we could cover our houses with solar cells, so that the entire structure, both inside and out, could harness solar energy for us.

These panels might not be as efficient as the current generation of solar cells, but quantity has the potential to make up for quality if we can cover a large enough area. Of course plants beat us to this innovation by twenty five million years, covering vast swathes of the planet in fields of self-replicating, flexible solar energy collectors, called grass. We might soon have the ability to do something similar in our urban environment. New research into the use of graphene for solar cells may provide just such a technology [1]

Graphene is a nanomaterial, a thin layer of carbon just one atom thick. It is strong and flexible, and very conductive. It is also largely transparent, meaning that it will allow a lot of light to enter the structure. These properties make it an excellent transparent electrode [2]. Creating transparent solar cells has been a goal of the solar industry for some time, so various research groups are working on using graphene to develop the next generation of organic photovoltaics.

So why would we want a transparent solar cell? Surely something that absorbs as much energy as possible would be best? This is certainly true, we want to absorb as much light as possible, but in practice a lot of the light that hits a solar panel is reflected rather than absorbed. A transparent cell would let this unused light through. Work is underway to incorporate graphene solar cells may soon be able to be worked into window glass, potentially adding photovoltaic surfaces all over our buildings [3].

They would also be able to absorb light from either side, rather than having to point in a single direction. Researchers at the University of Surrey have designed graphene solar cells modelled on the light capturing structure of moth’s eyes, in order to maximise the amount of light that the system can absorb. Nanotexturing of the material will channel light between the carbon nanostructures, increasing the amount of light that is absorbed and increasing the output of the device [1, 4].

There are a variety of ways that flexible and transparent solar cells can be produced, but graphene has a distinct advantage. It is made of carbon, which is a readily available resource. A lot of the materials that go into producing the current generation of solar panels are expensive and difficult to extract, these include the rare earth elements, which are required for a variety of electronics. These are hard to obtain, and their manufacture has a large impact on the environment as a result of pollution [5, 6]. Graphene is still energy intensive to make, and it is unlikely that we will ever get away from using rare earth elements entirely, but it may be a better option than similar systems using indium tin oxides and similar materials.

If flexible solar cells can be manufactured cheaply enough then they could be incorporated into wallpaper and building materials, providing our buildings with a photovoltaic skin, which can harness energy from every square metre of the structure.

References

  1. The Telegraph
  2. Graphene Info
  3. Clean Technica
  4. The Independent
  5. Hong Kong Polytechnic University
  6. Phys.org

Image Credit: AlexanderAlUS via flickr

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