High-brightness cyan-emitting Eu2+-activated orthophosphate phosphors for near-UV-pumped white LEDs

Abstract Near-ultraviolet (near-UV) pumped white light-emitting diodes (w-LEDs) based on tri-color (blue/green/red) phosphors have been regarded as an important approach to realize high-quality solid-state lighting, but the cyan gap between the blue and green phosphors imposes a limitation on the color rendering index. To solve this problem, efficient cyan phosphors with emission peaking around 490 nm and broad absorption band in the near-ultraviolet range are urgently needed. Herein, we demonstrate an efficient near-UV-excitable cyan-emitting LiBaPO4:Eu2+ orthophosphate phosphor for high-color-rendering w-LEDs. The prepared LiBaPO4:Eu2+ phosphors show a broad excitation band in the wavelength range of 250–450 nm peaking at 353 nm. Under 353 nm excitation, LiBaPO4:Eu2+ phosphors produce a wide cyan emission band in the wavelength range of 400–700 nm with a peak about 485 nm and band width of 99 nm. More importantly, LiBaPO4:Eu2+ phosphors exhibit a high internal quantum efficiency of 88.3%. A w-LED device is fabricated with a 365 nm near-UV LED chip with LiBaPO4:Eu2+ cyan phosphors and commercial CaAlSiN3:Eu2+ red phosphors, which demonstrates bright white emission with a color rendering index of 84.2 and correlated color temperature of 5243 K.