The photovoltaic effect takes place only a) hv>Eg b) hv=Eg c) hv
Answers
Answer:
The photovoltaic effect is the generation of voltage and electric current in a material upon exposure to light. It is a physical and chemical phenomenon.[1]
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 now usually used when the electron is ejected out of the material (usually into a vacuum) and photovoltaic effect 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 device concepts blur this distinction.
The first demonstration of the photovoltaic effect, by Edmond Becquerel in 1839, used an electrochemical cell. He explained his discovery in Comptes rendus de l'Académie des sciences, "the production of an electric current when two plates of platinum or gold immersed in an acid, neutral, or alkaline solution are exposed in an uneven way to solar radiation."[2]
The first solar cell, consisting of a layer of selenium covered with a thin film of gold, was experimented by Charles Fritts in 1884, but it had a very poor efficiency.[3] However, the most familiar form of the photovoltaic effect uses solid-state devices, mainly in photodiodes. When sunlight or other sufficiently energetic light is incident upon the photodiode, the electrons present in the valence band absorb energy and, being excited, jump to the conduction band and become free. These excited electrons diffuse, and some reach the rectifying junction (usually a diode p-n junction) where they are accelerated into the n-type semiconductor material by the built-in potential (Galvani potential). This generates an electromotive force and an electrical current, and thus some of the light energy is converted into electric energy. The photovoltaic effect can also occur when two photons are absorbed simultaneously in a process called two-photon photovoltaic effect.
Answer:
The photovoltaic effect is the development of voltage and current in a material when exposed to light. It is a physico-chemical phenomenon. The photovoltaic effect is closely related to the photoelectric effect. In both phenomena, light is absorbed and electrons or other charge carriers are excited to higher energy states. The main difference is that the term photoelectric effect is usually used when electrons are emitted from a material (usually into a vacuum), and the term photoelectric effect is used when excited charge carriers are still contained in the material. That is. In either case, the potential (or voltage) is produced by charge separation, and the light must have enough energy to overcome the potential barrier to excitation. The physical essence of the difference is usually that photoemission separates charges by ballistic conduction and photoemission separates them by diffusion, although some concepts of 'hot carrier' photovoltaic devices make this distinction Ambiguous. The first demonstration of the photovoltaic effect by his Edmond Becquerel in 1839 used an electrochemical cell. He wrote of his findings in his Comptes rendus de l'Académiedes sciences that "his two platinum or gold plates immersed in acidic, neutral, or alkaline solutions were unevenly exposed to solar radiation. When the voltage rises, a current is generated.” The first solar cell consisting of a layer of selenium covered with a thin layer of gold was experimented by Charles Fritt in 1884, but the efficiency was very low. In the form of , solid-state devices are used, primarily photodiodes. When sunlight or other sufficiently high-energy light hits the photodiode, the electrons residing in the valence band absorb the energy and are excited to jump free into the conduction band. These excited electrons diffuse and some reach the rectifying junction (usually the pn junction of a diode) where they are accelerated by the built-in potential (galvanic potential) into the n-type semiconductor material. This creates an electromotive force and current, converting some of the light energy into electrical energy. The photovoltaic effect also occurs when two photons are absorbed simultaneously in a process called the two-photon photovoltaic effect.
Explanation:
The photovoltaic effect occurs in solar cells. ... these photons can be absorbed by photovoltaic cells (the types of cells that make up a solar panel). When light of the appropriate wavelength is incident on these cells, energy is transferred from photons to the atoms of the semiconductor material in the pn junction.
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