The photovoltaic effect is the creation of voltage or electric current in a material upon exposure to light. Though the photovoltaic effect is directly related to the photoelectric effect, they are different processes. In the photoelectric effect, electrons are ejected from a material's surface upon exposure to radiation. The photovoltaic effect differs in that electrons are transferred between different bands (i.e., from the valence to conduction bands) within the material, resulting in the buildup of voltage between two electrodes.[1]
In most photovoltaic applications the radiation is sunlight, which is why the devices are known as solar cells. In the case of a p-n junction solar cell, illuminating the material creates 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.[2]
The photovoltaic effect was first observed by Alexandre-Edmond Becquerel in 1839.[3][4]
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