In the mid 1990s when the first high-brightness blue LEDs were first revealed, they were actually meant to be representative of bright white light. Technology has advanced since then, but many people still remember the efforts to create high powered white light and ask, Why do LED lights look blue? While those attempts were the beginnings of the ultra bright white LED lights as we know them today, the fact of the matter is, they were still far on the blue side of the spectrum.
Intent Vs. Accident
Today LED lights are blue for one of two reasons. The first and most obvious reason is because the manufacturer developed the light to be blue. However, there are times when inferior quality LEDs are manufactured that were intended to be bright white, but the result was much the same as early attempts. In other words, the second answer to the question, Why do LED lights look blue? is that it is merely accidental.
Type of Diode
One of the factors that determines the color of the light that is emitted by LED lights is the diode or diodes from which the light is manufactured. Each diode can only emit one color of the light spectrum, so in order to get any color other than the primary colors of the spectrum, more than one diode is lit at the same time. Diodes that produce blue light usually have a clear coating.
Wavelength
Each color of the rainbow has a very specific wavelength that determines the exact color, or shades of a color. Why do LED lights look blue? Thats because the energy that is emitted falls within the wavelength that determines the color blue. That wavelength is 450 and 500 nanometers.
Voltage
A certain amount of voltage is applied to the diode, and that voltage is also a contributing factor to the color that will be resultant. For instance, the diode that produces the color blue needs a wavelength of 450 to 500 nm. In order to produce that wavelength, a voltage of 2.48 and 3.7 volts must be applied to the blue diode.
Semiconductor Material
One very important facet of light emitting diodes is that they are not all made of the exact same materials. The diodes that emit blue light are manufactured with zinc selenide, indium gallium nitride, silicon carbide and silicon as a substrate. While other diodes that emit other colors may have one or more of those substances in them, they will not be exactly the same.
Why do LED lights look blue? With todays technology, it is a pretty good guess that they look blue because they are meant to look blue. Quite often LED lights are manufactured to produce bright blue-white light, and in those cases, it is only natural that the light would tend to look bluish. Unfortunately, there are still less expensive LED lights that do not utilize the most recent advances in LED technology. In these cases, it may be that the light that was meant to be bright white, but ended up on the blue end of the spectrum.
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