Light by voltage

Does anyone know if there is light emitting hardware out there that changes the color of light depending on the voltage applied. For example this special type of oh say...an LED changes color depending on the voltage applied. Higher voltages and the LED would emit blue, and lower voltages it would emit red, or whatever. Doesn't have to be an led. Just curious.

A RGB multi-colored LED can be driven by external circuitry to work in that way...

You can change color of an LED by slowly increasing forward current beyond the nominal current.

A red LED will slowly turn amber and finally - off (burnt up).

If you leave the chemistry inside the LED enough time to adapt to over current you can also create an LED lamp to be operated like a light bulb saving on the current limiting resistor.

Boncuk