A paper (linked below) by Nick Holonyak Jr. and S.F. Bevacqua is published in the journal Applied Physics Letters. It showed how a light-emitting diode (LED) could display the color red.
From www.techterms.com:An LED is an electronic device that emits light when an electrical current is passed through it. LEDs are commonly used for indicator lights (such as power on/off lights) on electronic devices. They also have several other applications, including electronic signs, clock displays and flashlights. Since LEDs are energy efficient and have a long lifespan (often more than 100,000 hours), they have begun to replace traditional light bulbs in several areas. Some examples include streetlights, the red lights on cars, and various types of decorative lighting.
Illustration from Encyclopedia Britannica.
* Holonyak and Bevacqua's paper: @