Synthesis and photoluminescence properties of near-UV-excitable cyan-emitting Ca2YHf2Ga3O12:Ce3+ garnet phosphors
In this study, in order to get near-ultraviolet-excitable cyan-emitting phosphors for white light-emitting diodes (LEDs), Ce 3+ ions were successfully doped into the newly discovered Ca 2 YHf 2 Ga 3 O 12 (CYHG) matrix through the high-temperature solid-state reactions. The obtained samples exhibited a broad excitation band in the 250–450 nm wavelength range centered at about 346 nm and 398 nm, and they showed an intense cyan emission band in the 410–600 nm wavelength range peaking at about 479–485 nm Ce 3+ doping concentration dependent luminescence properties in CYHG: x Ce 3+ phosphors were studied, and the optimal Ce 3+ doping concentration was found to be x = 0.04. Furthermore, the energy transfer mechanism between Ce 3+ ions was confirmed as the dipole-dipole interaction, which induced the observed concentration quenching effect. Notably, upon excitation by near-ultraviolet light at 398 nm, the CIE chromaticity coordinates of CYHG:0.04Ce 3+ sample were obtained to be (0.182, 0.276), which were located in the cyan color range. Besides, the internal quantum efficiency (IQE) values of these CYHG: x Ce 3+ phosphors were measured, and the highest one reached up to 26%. These newly developed cyan-emitting CYHG:Ce 3+ phosphors might find potential application in high-color-rendering white LEDs by covering the so-called cyan gap.
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