Eu2+-doped halo-phosphate/borate phosphors for color temperature tunable near UV-based white light-emitting diodes

Two halo-phosphate/borate phosphors, blue-emitting CaCl apatite:Eu2+ (CCAP:Eu2+) and yellow-emitting Ca2BO3Cl:Eu2+, were synthesized and used as down-conversion luminescent materials to fabricate a series of white light-emitting diodes (WLEDs) with near-UV LEDs, and their optical properties were investigated. Adjustable correlated color temperature can be realized by simply controlling the blending ratio of the blue and yellow phosphors. The fabricated white LEDs exhibited promising properties, including a high current durability, a wide range of tunable correlated color temperature (4000–8000 K), acceptable color rendering index (78–86).