Single-Phased White Phosphor for White Light Emitting Diodes

White light emitting diodes (WLEDs) are described as the new generation illuminate lamps and have already been used widely in many areas. Single-phased white phosphors excited by ultraviolet-near-ultraviolet (NUV) for WLEDs has become a hot topic in light-conversion materials for their distinctive advantages. Research and development of single-phased white phosphors for WLEDs is of great significance. In this paper, the research progress on single-phased white phosphors both at home and abroad is reviewed comprehensively. The methods to obtain the single-phased white phosphors are introduced. First, some rare earth ions, such as Eu2+, Eu3+ and Ce3+, can offer the possibility of simultaneous emission in the blue, green, orange and red wavelengths in different crystalline hosts. The second method is the combination of the intrinsic host emission (VO43-, MoO42-, or WO42-) band with the emission of rare earth ions. The third method is based on the energy transfer between different activators in some hosts. Then the mono ion doped single-phased white phosphors, including Eu2+-, Eu3+- Ce3+-, Dy3+-, Sm3+-activated phosphors, are presented in detail. Works on Eu2+/Mn2+, Eu2+/Ce3+ Ce3+/Mn2+ Tm3+/Dy3+, Eu3+/Dy3+-coactivated single-phased white phosphors are also summarized. In addition, multiple ions-coactivated single-phased white phosphors are reviewed. The photoluminescence spectra and their tunable mechanism of relevant silicate, chlorosilicate, phosphate, borate, aluminate, etc. are described briefly. Moreover, the current problems existing in this field are pointed out and a brief prospect is provided.