Photovoltaic effect

Not to be confused with Photoelectric effect.

The photovoltaic effect is a physical phenomenon in which a semiconductor material generates electric energy upon being exposed to light.

The photovoltaic effect is closely related to the photoelectric effect. For both phenomena, light is absorbed, causing excitation of an electron or other charge carrier to a higher-energy state. The main distinction is that the term photoelectric effect is usually used when the electron is ejected out of the material (usually into a vacuum), and photovoltaic effect is used when the excited charge carrier is still contained within the material. In either case, an electric potential (or voltage) is produced by the separation of charges, and the light has to have a sufficient energy to overcome the potential barrier for excitation. The physical essence of the difference is usually that photoelectric emission separates the charges by ballistic conduction and photovoltaic emission separates them by diffusion, but some "hot carrier" photovoltaic devices concepts blur this distinction.

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