All carbon solar cell (via Stanford)
Solar cells come in many different flavors and are traditionally made with any number of silicon materials, such as monocrystalline silicon, polycrystalline silicon and amorphous silicon (to name a few), but now scientists from Stanford University have succeeded in adding a new material to the solar cell mix in the form of carbon. Most solar cells use rare-earth metals in their make-up for the cells electrodes such as ITO (indium tin oxide) and silver which are extremely costly and will not last forever (according to China who exports 90% of the world’s supply). This fact alone makes Stanford’s thin-film solar cell an attractive prospect to manufacturers as the cost of materials are reduced along with a reduced amount of steps to fabricate the cells. To make the all carbon photovoltaic cell, Stanford’s scientists replaced the silver and indium tin oxide electrodes with graphene along with single-walled carbon nan-tubes, which have outstanding electrical conductivity as well as excellent light gathering properties. For the cells light-absorbing layer, the scientists used a carbon mixture containing nano-tubes and buckyballs (a carbon soccer-ball cage-like fused ring structure) which primarily gathers light from the infrared wavelength of the spectrum making the cell inefficient (taken from a laboratory conversion efficiency of less than 1 percent) over it’s more common counterparts (more on this later).
Stanford’s scientists state that their thin-film carbon solar cell can be applied through a unique solution to various surfaces including rooftops, windows or even cars to help generate electricity. However the questio0n of inefficiency still remains but the team states that they are looking at ways of improving the cell’s only drawback. One of the way’s the scientists are considering is to smooth the graphene material by re-stacking the nano-structures in a more compact efficient manner, which would make it easier to collect an electrical current. Another prospect the team is looking at is experimenting with different carbon nano-materials that are able to absorb light in a wider-range of wavelengths including those in the visible spectrum. While you may not see these carbon-based solar cells anytime soon, in the commercial market they do have promise as it stands right now. Carbon is extremely durable and remains stable in harsh conditions including heat (up to 1,1000 Fahrenheit) where function is the priority rather than form and efficiency. This means with a little tweaking these cells could be implemented in environments such as space, deserts and oceans (saltwater corrodes just about everything you can imagine) in the near future.
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