Photovoltaic effect

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The photovoltaic effect involves the creation of a voltage (or a corresponding electric current) in a material upon exposure to electro-magenetic radiation. Though the process is directly related to the photoelectric effect the two processes are different and should be distinguished. In the photoelectric effect electrons are ejected from a materials surface upon exposure to radiation of sufficient energy. The photovoltaic effect is different in that the generated electrons are transferred from one material to another resulting in the buildup of a voltage difference between two electrodes.

In most photovoltaic applications the radiation is sunlight and for this reason the devices making use of the photovoltaic effect to convert solar energy into electrical energy are know as solar cells. In the case of a p-n junction solar cell, illumination of the material results in the creation of an electric current as excited electrons and the remaining holes are swept in different directions by the built in electric field of the depletion region.