Patent ID: 6953536

Claim:
A method for generating long persistent phosphorescence at a selected color comprising the steps of: a) selecting at least a first activator capable of producing long persistent phosphorescence of a first color when incorporated with a co-activator into a host; b) selecting at least a second activator capable of producing long persistent phosphorescence of the selected color when incorporated into the host with the first activator and the co-activator, the second activator being capable of accepting energy from the first activator; c) fabricating a long-persistent phosphor comprising the second activator, the first activator and the co activator incorporated into the host; and d) irradiating the long-persistent phosphor, thereby producing long-persistent phosphorescence of the selected color, wherein the first activator, the second activator, and the co-activator are all different ions and the first color is different from the selected color and the host is an alkaline-earth aluminate or an alkaline-earth aluminosilicate.