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The following table shows the available colors with wavelength range, voltage drop and material: ... (about 1.7 V for a red LED or 1.2V for an infrared) ...
The wavelength of the light emitted is a function of the band gap of the semiconductor material used; materials such as gallium arsenide, and others, with various trace doping elements, are used to produce different colors of light. Another type of LED uses a quantum dot which can have its properties and wavelength adjusted by its size. Light ...
is the LED's forward voltage drop in volts when lit. and the LED's light frequency (which we perceive as color) increase with the band gap of the LED's materials. Consequently, ranges from around 1.7 to 2.0 volts for red LEDs to around 2.8 to 4.0 volts for violet LEDs.
LEDs produce wavelengths that span from UV-A (350 nm) to near-infrared (NIR) (1100 nm). [14] The wavelength of the LED light can target different tissues. Long wavelength lights such as NIR/dark red(600-1000 nm) can have better tissue penetration and can easily absorb cytochrome c oxidase (CCO) targets by PBMT.
In frequency (and thus energy), UV rays sit between the violet end of the visible spectrum and the X-ray range. The UV wavelength spectrum ranges from 399 nm to 10 nm and is divided into 3 sections: UVA, UVB, and UVC. UV is the lowest energy range energetic enough to ionize atoms, separating electrons from them, and thus causing chemical reactions.
The direct bandgap of AlGaInP encompasses the energy range of visible light (1.7 eV - 3.1 eV). By selecting a specific composition of AlGaInP, the bandgap can be selected to correspond to the energy of a specific wavelength of visible light. For instance, this can be used to obtain LEDs that emit red, orange, or yellow light. [1]
LED-B1 through B5 defines LEDs with phosphor-converted blue light. LED-BH1 defines a blend of phosphor-converted blue and a red LED. LED-RGB1 defines the white light produced by a tricolor LED mix. LED-V1 and V2 define LEDs with phosphor-converted violet light.
QD-LED structure can be tuned over the entire visible wavelength range from 460 nm (blue) to 650 nm (red) (the human eye can detect light from 380 to 750 nm). The emission wavelengths have been continuously extended to UV and NIR range by tailoring the chemical composition of the QDs and device structure. [80] [81]