It is a dopant in some types of glass in lasers and other optoelectronic devices . Europium oxide ( Eu2O3 ) is widely used as a red phosphor in television sets and fluorescent lamps , and as an activator for yttrium @-@ based phosphors . Color TV screens contain between 0 @.@ 5 and 1 g of europium oxide . Whereas trivalent europium give red phosphors , the luminescence of divalent europium depend on the host lattice , but tend to be on the blue side . The two classes of europium @-@ based phosphor ( red and blue ) , combined with the yellow / green terbium phosphors give " white " light , the color temperature of which can be varied by altering the proportion or specific composition of the individual phosphors . This phosphor system is typically encountered in helical fluorescent light bulbs . Combining the same three classes is one way to make trichromatic systems in TV and computer screens . Europium is also used in the manufacture of fluorescent glass . One of the more common persistent after @-@ glow phosphors besides copper @-@ doped zinc sulfide is europium @-@ doped strontium aluminate . Europium fluorescence is used to interrogate biomolecular interactions in drug @-@ discovery screens . It is also used in the anti @-@ counterfeiting phosphors in euro banknotes .