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

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 nearultraviolet 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 bandwidth 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.

Automated summary

Near-ultraviolet pumped white light-emitting diodes based on tri-color phosphors are important for high-quality solid-state lighting, but the cyan gap between blue and green phosphors poses a limitation on color rendering index. Efforts are needed to develop efficient cyan phosphors with emission peaking around 490 nm to address this issue.