Applications of rare earth in full-colour EL displays

The use of rare earth containing phosphors in a.c. operated thin film electroluminescent (ACTFEL) displays is reviewed. Rare earth ions are needed to produce the blue, green and red emission colours necessary for full-colour devices. ZnS:Tb super(3+) is the green material used today and it has been developed to a level sufficient for technical applications. SrS:Ce super(3+) has been investigated as blue-emitting phosphor and both CaS:Eu super(2+) and ZnS:Sm super(3+) have been used as red phosphors. The blue and red phosphors, however, still need improvements in brightness and stability before they can be applied in TFEL devices. White electroluminescence can be obtained from SrS:Ce super(3+), Eu super(2+) and SrS:Pr super(3+) materials but their luminance is not yet high enough for practical applications.