How Photovoltaic (Solar) Cells Work


solar panelsPhoto:
image: twentyeight

All photovoltaic panels function on one basic principle of nature, the photoelectric effect, according to which matter emits electrons whenever it absorbs energy contained in electromagnetic radiation, namely sunlight. The motion of these so-called photoelectrons is what generates electric current.

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Illustration of the photoelectric effect. image: University Of Iceland

In the Chemistry department of Ohio State University something good happened. Researchers managed to create a new substance – combining titanium, molybdenum and conductive plastic, that has the ability to absorb light from the entire range of the solar spectrum. Regarding that the speed of released photoelectrons (and thus quantity of produced current) depends only on the range of radiation, the material is considered perfectly suitable for the construction of solar cells capable of achieving 100% efficiency, i.e. convert all light they can take into electricity.

Utilizing one of the university’s supercomputers, the scientists adjusted numerous molecular structures until they stumbled upon the specific one. Afterwards their colleagues in National Taiwan University manufactured a sample of the substance and experiments initiated. One basic problem faced by photovoltaic technology is that the knocked loose electrons remain free for only a tiny fraction of a second. This makes the capturing procedure, called charge separation, extremely difficult. Remarkably, a certain class of excited electrons (identified as triplet state) of the new material remained unattached 7 million times longer than electrons within common solar cells, a fact which shall greatly ameliorate charge separation.

solar panels - housePhoto:
image: inhabitat

Although yet years away from massive implementation due to production cost, it is estimated that such revolutionary materials could lead the field of renewable energy in the forthcoming future.

Sources: 1, 2, 3, 4, 5, “Physics” by Alonso and Finn

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