quantum yield

physics and electronics

Also known as: photoelectric yield, quantum efficiency

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July 13, 2026

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Quantum efficiency, also known as quantum yield, is a measure in physics and electronics that represents the ratio of the number of electrons released in a photoelectric process to the number of radiation quanta absorbed. It can also refer to the efficiency of luminescence emission, considered on both an energy and quantum basis.12

In some instances, such as resonance excitation, the quantum efficiency can be 100 percent. However, in most luminescent processes, it is significantly lower. For example, zinc sulfide phosphors have an efficiency of about 20 percent. Quantum electronics is a branch of physics focused on the interaction of radiation with discrete energy levels within substances, as seen in devices like masers and lasers.23

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radiation measurement
Scintillators
…fraction is known as the quantum efficiency of the light sensor. In a silicon photodiode, as many as 80 to 90 percent of the light photons are converted to electron-hole pairs, but in a photomultiplier tube, only about 25 percent of the photons are converted to photoelectrons at the wavelength…
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…fraction is known as the quantum efficiency of the light sensor. In a silicon photodiode, as many as 80 to 90 percent of the light photons are converted to electron-hole pairs, but in a photomultiplier tube, only about 25 percent of the photons are converted to photoelectrons at the wavelength…
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radiation
The photoelectric effect
The photoelectric yield, defined as the ratio of the number of photoelectrons to that of incident photons, serves as a measure of the efficiency of the process. Photoelectric yield starts from a zero value at threshold, reaches a maximum value (about 1/1,000) at about twice the…
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The photoelectric yield, defined as the ratio of the number of photoelectrons to that of incident photons, serves as a measure of the efficiency of the process. Photoelectric yield starts from a zero value at threshold, reaches a maximum value (about 1/1,000) at about twice the…
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radiation measurement
Conversion of light to charge
The quantum efficiency of the photocathode is defined as the probability for this conversion to occur. It is a strong function of wavelength of the incident light, and an effort is made to match the spectral response of the photocathode to the emission spectrum of the…
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The quantum efficiency of the photocathode is defined as the probability for this conversion to occur. It is a strong function of wavelength of the incident light, and an effort is made to match the spectral response of the photocathode to the emission spectrum of the…
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photochemical reaction
Consequences of photoexcitation
The quantum yield of luminescence, either fluorescence or phosphorescence, is the fraction of the absorbed radiation that appears as that luminescence. Quantum yields are less than 100 percent owing to nonradiative processes (e.g., internal conversion) that dissipate the excess internal energy acquired from the absorbed photon.…
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The quantum yield of luminescence, either fluorescence or phosphorescence, is the fraction of the absorbed radiation that appears as that luminescence. Quantum yields are less than 100 percent owing to nonradiative processes (e.g., internal conversion) that dissipate the excess internal energy acquired from the absorbed photon.…
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