Glow-in-the-dark materials that shine with the whole range of visible colours, and can even produce white light, have been developed by Japanese researchers.
"Conventional blue or green phosphors create an eerily uncomfortable illumination environment in which people feel anxiety," Saito explains. They also give poor contrast when used for signs which is a problem when people need to find exits through heavy smoke or dust, he says.
Warmer colours like orange and red will produce more legible signs. "Combining red, green, and blue colours even enables us to create white light, which may provide more natural illumination," Saito says.
Full-colour glow-in-the-dark materials unveiled