EL Material Can Generate Both Red and Green Light
Burstwave writes "According to this story, investigators at Philips, in collaboration with researchers at the University of Amsterdam, have developed the first electrochemiluminescent material that can generate both red and green light, an effect that depends on current flow. The full report will appear in Nature on Monday. This significant advance in ECL technology will lead to smaller and brighter full-color LED displays."
I'm no material scientist, but you could try putting an AC current through it at a rate that is higher than the eye could distinguish the two colours.
Now, I'll add here that I am no expert on any of these things and this post is just me speaking through my arse.
The colorblind can at least differentiate between red and green lights by the position of the illuminated light (top or bottom) the way it is now. If both were in the same spot, I can't say I'd feel more safe with the couple hundred dollars it may save the city.