Recent Progress of Single-phase White Light-emitting Diodes Phosphors

As a new solid-state lighting source, the white light-emitting diodes (WLEDs) have a greatly promising application in the field of lighting and display. They have superior advantages of high luminous efficacy, fast response speed and long service life, etc. compared with the existing light sources (incandescent lamps, fluorescent lamps, etc.). At present the WLEDs are commonly fabricated by combination of a blue LED chip and YAG: Ce 3+ yellow-emitting phosphor, and combination of a ultraviolet-near ultraviolet excitation chip and red-green-blue (RGB) emitting color phosphors, compared with the above two phosphors, the single-phase phosphors containing white emission have the advantages of a higher luminous efficacy, color rendering. Meanwhile, the single-phase phosphors may effectively solve the reabsorption problem existing in RGB phosphors. There have been a large number of reports on the research of single-phase phosphors, involving a variety of material systems. According to the principle of luminescence, it can be simply divided into three groups: single ion doped system, multi-ion doped system and other systems which do not rely on rare earth ion to light. This paper reviews the research progress of single-matrix WLEDs phosphors, and points out the problems in their development, and forecasts the future development trend.