Achieving full-visible-spectrum LED lighting via employing an efficient Ce3+-activated cyan phosphor

At present, near-ultraviolet-pumped white light-emitting diodes (LEDs) based on tri-color (blue, green, and red) phosphors still suffer from insufficient color rendering index (CRI), due to the presence of cyan gap in the 480–520 nm spectral range. To solve this problem, it is urgent to develop an efficient cyan phosphor with emission peak around 490 nm and absorption band in the near-ultraviolet range of 380–420 nm. Herein, a highly efficient cyan-emitting Ca2GdHf2(AlO4)3:Ce3+ (CGHA:Ce3+) garnet phosphor with internal quantum efficiency as great as 80% is reported. Impressively, the CGHA:1%Ce3+ sample showed a broad excitation band ranging from 350 to 470 nm with a maximum at 408 nm, and upon 408 nm excitation it exhibited an intense broad cyan emission band in the 420–700 nm wavelength range with peak at 489 nm and a full width at half-maximum of 103 nm. Importantly, by applying the newly discovered cyan-emitting CGHA:1%Ce3+ phosphors as color converter, the CRI value of the fabricated warm-white LED device is greatly enhanced from 80.5 to 91.6. This work demonstrates that the novel developed CGHA:Ce3+ cyan phosphors could compensate for the cyan gap and realize full-visible-spectrum lighting, which have a bright prospect in high-quality solid-state white lighting.