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Quantum efficiency (QE) is a quantity defined for a photosensitive device such as photographic film or a charge-coupled device (CCD) as the percentage of photons hitting the photoreactive surface that will produce an electron-hole pair. It is an accurate measurement of the device's sensitivity. It is often measured over a range of different wavelengths to characterize a device's efficiency at each energy. Photographic film typically has a QE of much less than 10%, while CCDs can have a QE of well over 90% at some wavelengths. Image File history File links Quantum_efficiency_graph_for_WFPC2. ...
Image File history File links Quantum_efficiency_graph_for_WFPC2. ...
Jump to: navigation, search The Hubble Space Telescope is a telescope in orbit around the Earth. ...
A Hubble Space Telescope image of the Hubble Deep Field showing the characteristic stairstep composition of WFPC2 images The Wide Field and Planetary Camera 2 (WFPC2) is a camera installed on the Hubble Space Telescope. ...
Undeveloped Arista black and white film, ISO 125. ...
Jump to: navigation, search A specially developed CCD used for ultraviolet imaging in a wire bonded package. ...
Jump to: navigation, search In physics, the photon (from Greek φοτος, meaning light) is a quantum of the electromagnetic field, for instance light. ...
Creation of Electron-Hole Pairs When ionizing radiation strikes a semiconductor, it will often excite an electron out of its energy level and consequently leave a hole. ...
Jump to: navigation, search The wavelength is the distance between repeating units of a wave pattern. ...
QE is a very important measure for solar cells as it gives information on the current that a given cell will produce when illuminated by a particular wavelength. If the quantum efficiency is integrated (summed) over the whole solar electromagnetic spectrum, one can evaluate the current that a cell will produce when exposed to white light. The ratio between this current and the highest possible current (if the QE was 100% over the whole spectrum) gives the electrical efficiency of the solar cell. With solar cells, one often meaures the external quantum efficiency, i.e. the current obtained outside the device per incoming photon. The external quantum efficiency therefore depends on both the absorption of light and the collection of charges. (Once a photon has been absorbed and has generated an electron-hole pair, these charges must be separated and collected at the junction. A good-quality material is crucial to avoid charge recombination and therefore a drop in the quantum efficiency.) A solar cell, a form of photovoltaic cell, is a device that uses the photoelectric effect to generate electricity from light, thus generating solar power (energy). ...
The Sun (occasionally referred to as Sol) is the star at the centre of our solar system. ...
Jump to: navigation, search The electromagnetic spectrum is the range of all possible electromagnetic radiation. ...
The efficiency of an entity (a device, component, or system) in electronics and electrical engineering is defined as useful power output divided by the total electrical power consumed (a fractional expression). ...
Absorption has a number of meanings: In physics, absorption is a process in which particles of some sort encounter another material and are taken up by or even disappear in it. ...
The responsivity is a similar measurement, but it has different units, A/W (Ampere/Watt); i.e how much current comes out of the device for an incoming light beam of a given power. Both the quantum efficiency and the responsivity are functions of the photons' wavelength. Jump to: navigation, search In electricity, current refers to electric current, which is the flow of electric charge. ...
To convert from responsivity to QE in %: where R is the responsivity in A/W at the wavelength λ, and λ, the wavelength, is in nm.
External links - Definition of Quantum Efficiency in Photonics Dictionary
- Definition of Responsivity in Photonics Dictionary
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