LED, or Light Emitting Diode, is a semiconductor chip composed of p-type and n-type semiconductors with a transition layer, known as the p-n junction, between them. In certain semiconductor materials, when injected minority carriers recombine with majority carriers at the p-n junction, excess energy is released in the form of light, directly converting electrical energy into light energy.
When an LED is in forward-biased state, current flows from the anode to the cathode, causing the semiconductor crystal to emit light ranging from ultraviolet to infrared, with the intensity of light being related to the current.
The spectral range of LED light sources is narrower than that of sunlight, mainly within specific single-color wavelength ranges. The spectrum wavelengths, from short to long, appear as blue, green, yellow-green, yellow, yellow-orange, and red. The typical peak wavelengths for several common colors are: ultraviolet 365 nm, blue 475 nm, cyan-green 500 nm, green 525 nm, yellow 590 nm, orange 610 nm, and red 625 nm.
White light from LEDs is generated by blue LEDs exciting yellow phosphors, resulting in energy loss around 480 nm. Therefore, white LEDs differ significantly from the solar spectrum. LED light sources are also measured in terms of color temperature: below 3000 K is considered warm, 3000-3300 K is warm white, 4000-4500 K is natural white, 6000-6500 K is cool white, and above 7000 K is cold white.
LED light sources are primarily used for single-wavelength conditions in photochemical research. In photochemical experiments, researchers often use single-wavelength LED light sources to investigate photocatalytic quantum efficiency. A commonly used device is the Perfectlight PLS-LED 100C high-power LED light source. This LED light source offers not only a white light series (with different color temperatures) and special lamp bead series, but also nearly 40 selectable single wavelengths covering the range of 365-940 nm.
Compared to mercury and xenon lamps, LED light sources offer advantages such as good monochromaticity, being a cool light source, long lifespan, energy efficiency, and environmental friendliness.
1. Good Monochromaticity
For single-wavelength LEDs, their full width at half maximum (FWHM) is related to the output wavelength, typically around 10 nm. This is lower than that of xenon lamps with filters. Therefore, when conducting quantum efficiency tests, LED light sources can more accurately calculate quantum efficiency.
2. Cool Light Source
LED light sources are cool light sources and produce almost no heat compared to the output light of xenon and mercury lamps. Therefore, when conducting photo-thermal catalytic experiments or when specific thermal output requirements are needed, LED light sources have a significant advantage. LED irradiation does not lead to significant temperature changes in the reaction system.
3. Long Lifespan
LEDs primarily emit light through the continuous movement of charge carriers, making aging and burnout phenomena virtually nonexistent. This emission mechanism ensures that LED light sources can have a lifespan of up to 10,000 hours, far exceeding that of xenon and mercury lamps.
4. Energy Efficiency
As mentioned earlier, LED light sources are cool light sources and produce almost no heat. Therefore, compared to other light sources that generate a lot of heat, LED light sources consume much less energy.
5. Environmental Friendliness
LEDs are solid-state light sources, highly resistant to impact and breakage. They produce recyclable waste and do not contain harmful elements such as mercury and xenon.
That's all about LED light sources. If you have any related questions, you can contact Perfectlight Technology via their official WeChat (Perfectlight2002) or call 400-1161-365 at any time.
