Some LED lights can change color, but it is not normally the LED that changes color. When you see an LED light change color, what you actually see is a different colored diode inside emitting the light.
Interested in how this is all possible? Here is a quick explanation on how LED lights change color (click here to learn how LEDs work).
Method 1: Color Changing LED Lights Using Several LED Colors
A Light Emitting Diode is essentially a semiconductor that releases energy in the form of light. The light color depends on the material of the semiconductor.
Most color changing LEDs contain three separate light emitting diodes in the same casing. Each LED emits its own specific color but by controlling the energy levels of these three LEDs, other colors can be created. This is known as the RGB color model.
Take for example a standard color changing LED with a red, blue and green LED inside the same casing (there are many other different types of LED lights on the market). Inside the casing is also a microcontroller that manages which LED receives a current.
A current to a single LED in this casing gives off either red, blue or green while a current to two LEDs results in a color combination like purple, pink, yellow and so on. This is commonly referred to as LED color temperature.
Method 2: Color Changing LED Lights Through Alternating Currents
Another way to control the color that an LED emits is by using alternating currents. In this case, a lower current is sent to the colored LED so that the shade changes.
For example, sending current at 100% brightness through a red LED gives off the color red. Then, lowering the brightness to only 50% gives the color pink.
This color effect is specific to LED technology. The same mechanism does not give the same results with halogen lights or a CFL for example.
You have probably noticed that other types of light bulbs need a few seconds to reach full brightness. An LED reaches full brightness instantly so there is no lag time, this is one of the many benefits of LED lighting.
The human eye cannot detect the rapid speed at which an LED turns on and off. Instead, humans detect the net result of the LED turning on and off at this extreme pace.
In other words, when an LED switches on and off at a steady fast pace, we humans only detect the light as being dimmer. This is why the red LED can appear as pink.
What you actually see is the red LED turning on and off so fast that your brain detects the color at 50% brightness, in this case, pink. Depending on the set pace of the LED, this shade that we register changes.
Common LED Colors and Their Materials
Different materials are used for different LED colors. Below is a quick overview of the common semiconductor materials used for color changing LED lights.
- Aluminium gallium indium phosphate (AIGaInP): yellow, orange and red
- Gallium Phosphide (GaP): yellow and green
- Indium Gallium Nitride (InGaN): green, blue and white
- Aluminium Gallium Arsenide (AIGaAs): red and infrared