Overcoming the cyan gap for full-spectrum lighting using cation-substitution-induced rigid Ca2YZr2Al3O12:Ce3+

Mixing multicolor phosphors for simulating the full spectrum of sunlight illumination is a popular solution to obtain high-quality white light. However, there is still a need to overcome the cyan gap in the emission spectrum. In this work, a series of garnet Ca2Y0.94-xLuxZr2-yHfyAl3O12:6%Ce3+ (abbreviated as CY(0.94-x)Lu(x)Zr(2-y)Hf(y)A:Ce3+) cyan phosphors are designed and prepared by substituting Y3+ and Zr4+ in Ca2YZr2Al3O12:6%Ce3+ with Lu3+ and Hf4+ with smaller ionic radius and larger mass. Under 405 nm violet light excitation, the optimized Ca2Y0.88Lu0.06Hf2Al3O12:6%Ce3+ (CY(0.88)Lu(0.06)Hf(2)A:Ce3+) shows a bright cyan emission band in the range of 430-750 nm with the peak at 477 nm. Importantly, the emission intensity and thermal stability properties of CY(0.88)Lu(0.06)Hf(2)A:Ce3+ were significantly improved by 58% and 47% compared to those of pure Ca2YZr2Al3O12:Ce3+. Small and heavy cation substitution could induce highly stable rigid structure, thus enhancing emission intensity and stability. The color rendering index increases from 84.5 to 92.0 after supplementing CY(0.88)Lu(0.06)Hf(2)A:Ce3+ phosphor in white light-emitting diode devices combining commercial red, green, and blue phosphors with a violet chip, indicating its practical application in full-spectrum lighting. The present study provides promising strategies for the design and development of efficient cyan materials for high-quality full visible spectrum light-emitting diode lighting.