How Do LEDs Change Color?

Heather Clouse
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Method 1: Color Changing LED Lights Using Several LED Colors

The color of an LED is determined by the spectrum of light produced when electrons in the semiconductor materials in the LED’s diode start jumping from orbit to orbit and getting back again.

If you choose a diode with a higher ratio of energy in the desired visible light, the light from the diode will be stronger in that color. This is because a lot of energy will get in at the desired wavelength and very little at the other wavelengths.

You can find LEDs that produce light at other wavelengths (including one that emits infrared, which is invisible to the human eye). But the green, red, and blue used in LED displays are the three primary colors that are the basic building blocks of all visible color.

Different colors of LEDs can be combined to produce any color visible to the human eye. The order in which the light is combined is important, because the human eye is most sensitive to green light. So if you mix it with any other color, it will become dominant.

To make a white light, you’d combine red and blue with the same time, with green afterwards.

Method 2: Color Changing LED Lights Through Alternating Currents

An Alternating Current (AC), is a continuous flow of electrons that changes direction periodically.

A regular light bulb uses Direct Current (DC) electrons, pushing electrons in one direction continuously.

If you apply a DC voltage on an LED, it will not light up.

However, if you use an AC current, the LED will light up. The AC current makes the electrons in the LED jump back and forth between different energy levels. This is the physics behind how LEDs work.

Common LED Colors and Their Materials

LEDs are made with different materials.

The main ones are GaAs (Gallium-Arsenide), InP (Indium Phosphide), AlGaAInP (GaAluminum-Gallium-Arsenide-Indium-Phosphide), GaInN (Gallium-Indium-Nitride), and Si (Silicon).

They are used in a wide range of colors. They are named after the color they emit.

To produce red light, LEDs are made of Gallium-Arsenide. Red, orange, and yellow are produced by AlGaAInP LEDs.

GaInN gives the color green while InP produces blue.

Silicon makes the color white while combinations of these elements make purple, pink, turquoise, and black.