Light-Induced Magnetism Could Fuel New Class of Solar Cells

The physical world gets really weird when you get to really small scales. In previous posts, I’ve mentioned the push to create computers and the instantaneous transmission of information using quantum mechanics and effects Einstein described as, “spooky.” But the world also behaves in strange ways on scales slightly bigger than the quantum universe, such as an atomic scale.

Take light, for example. It behaves as both a wave and a particle, and has many properties that scientists are still struggling to comprehend. For example, a polarized beam of light creates a small electric field that can be harnessed by modern solar cells. It also creates a small magnetic field, but one so tiny that its effects can be neglected.

Or can they?

Stephen Rand, a professor in the departments of Electrical Engineering and Computer Science, Physics and Applied Physics at the University of Michigan, recently published a paper in the Journal of Applied Physics that makes use of this mostly overlooked effect in order to create an electrical current. In theory, the magnetic field could be used to create solar cells and batteries that don’t use semiconductors. In fact, they would have to use insulators.

Think about that for a second. Electric currents and batteries formed in non-conductive materials (no metals here!) by the mere presence of sunlight.

It works by affecting the orbits of electrons around atoms in the non-conductive material. The magnetic field pushes the electron away from the nucleus, causing a C-shape that gets a little more curved each time around. And because an electron is negatively charged, the asymmetric orbit sets up an electric dipole; there is more negative energy on one side than the other. Setting a bunch of these in a row along a fiber can make a voltage big enough to extract and use as a power source.

Being able to harness this effect could mean great cost savings for the solar panel industry. According to their calculations, efficiencies as high as 10% – which is what modern commercial solar cells achieve – is well within reason. Throw in the fact that the system would use materials like glass, which is already made in bulk and doesn’t require much processing, and you end up with a potentially cheap alternative to modern solar cells.

But what’s the catch, you ask? I mean come on, there’s always a catch.

Well there is.

The intensity of light needed to make this idea a reality hovers somewhere around the 10 million watts per square centimeter mark. If that sounds like a shitload, that’s because it is. The typical intensity of sunlight hitting the Earth’s surface hovers around .13 watts per square centimeter. I don’t know how high of an intensity things like thermal towers and curved mirrors can achieve, but I’m guessing it’s nowhere near the 1-billion-times-as-intense-as-regular-sunlight-mark needed for this theory to work.

But never say never. Rand and his team are looking into other materials that could produce electricity at much lower intensities, like transparent ceramics. Still, I wouldn’t hold my breath on seeing them on the shelves of Walmart anytime soon.


About bigkingken

A science writer dedicated to proving that the Big Ten - or the Committee on Institutional Cooperation, if you will - is more than athletics.
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