L16-Solar_Cells

L16-Solar_Cells - Nanoparticle Enhanced Thin Film Solar...

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Nanoparticle Enhanced Thin Film Solar Cells
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Solar Cells Solar cells convert visible light to electricity. It is one of the “clean” sources of energy. In theory a 100 square mile area covered with solar panels would be sufficient for the energy needs of the US. Solar cells are based on the photovoltaic effect.
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Photovoltaic Effect Discovered in 1839 as a light induced current between two metal electrodes. When photons are absorbed in a material, some electrons gain enough energy to become free and contribute to current. If the light is incident on a p-n junction, the absorbed photon creates an electron-hole pair.
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p-n Junction Solar Cells Most commonly made of crystalline silicon by diffusing an n-type layer into a p-type substrate (or vice versa). When a p-n junction is formed, near the junction, the extra electrons from the n- side are attracted to the extra holes from the p-side. As the two sides rush towards each other, a neutral depletion layer is formed with a built-in electric field that opposes any further charge movement. When light is incident on the junction, each absorbed photon creates an electron-hole pair. The electrons and holes are separated by the built-in electric field at the junction. The electrons move to the n-side and the holes to the p-side and create a potential difference. If the device is connected to an external load, a current will flow.
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L16-Solar_Cells - Nanoparticle Enhanced Thin Film Solar...

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