Phosphors for flat panel field emission and plasma displays

Summary form only given, as follows. Truly emissive flat panel displays have long been sought, and have faced many technological challenges, but are now very close to becoming a commercial reality. A review is given of the recent developments of phosphors for low to medium voltage applications in field emission displays (FED) and in new plasma display panels (PDP). For FEDs the drive to operate at lower voltage and power, is frustrated by the rapid decrease in phosphor luminous efficiency. This is due to the smaller volume of luminescent activators that are sampled at low electron beam voltages and by the presence of non-radiative surface recombination effects. The higher drive currents possible from a field emission device can be used to compensate for this loss in brightness and efficiency, but for many current phosphors, saturation and coulombic degradation limit the advantage of high current sources. The use of fast activators and a more complete understanding of electron-solid interactions at low voltages is shown to be necessary to characterize and develop solutions to this problem. In PDP the switch to xenon plasma excitation sources requires further phosphor optimization to achieve the same efficiencies when pumped by 150-180 nm radiation, than the 254 nm Hg discharge used in lighting, but many existing phosphors have acceptable properties for current applications. There is, however, a need to increase phosphor lifetimes in a display by developing coating techniques. Additionally, an improved red chromaticity and a faster green phosphor to prevent smearing, are desired as well as a more efficient blue phosphor. Recent progress in this area and the search for more power efficient plasma phosphors will be discussed.