Highly Efficient Broad-Band Green-Emitting Cerium(III)-Activated Garnet Phosphor Allows the Fabrication of Blue-Chip-Based Warm-White LED Device with a Superior Color Rendering Index

Abstract

High-performance warm-white light-emitting diode (LED) devices are in great demand toward green and comfortable solid-state lighting. Herein, we report a creative green-emission CaY 2 HfGa(AlO 4 ) 3 :Ce 3+ phosphor. CaY 2 HfGa(AlO 4 ) 3 :Ce 3+ compounds with different cerium ion doping contents have been successfully prepared through a conventional high-temperature solid-state method, and their phase and crystal structure have been revealed via the powder X-ray diffraction and Rietveld refinement. Impressively, the CaY 2 HfGa(AlO 4 ) 3 :Ce 3+ phosphors exhibit a broad-band excitation, which well covers the wavelength region from the 300 to 500 nm, corresponding to the commercial blueemitting LED chip. Upon 450 nm excitation, the optimal CaY 2 HfGa(AlO 4 ) 3 :2%Ce 3+ sample shows an intense broad-band green emission (the corresponding testing spectral range: 460− 750 nm) with a strongest peak about 534 nm. In addition, the CaY 2 HfGa(AlO 4 ) 3 :2%Ce 3+ sample possesses a broad full width at halfmaximum equal to 120 nm; moreover, its CIE chromaticity coordinate and the internal quantum efficiency are determined to be (0.3541, 0.5427) and 72.8%, respectively. A high-quality warm-white LED has been fabricated through incorporating our CaY 2 HfGa(AlO 4 ) 3 :2%Ce 3+ green phosphors and commercial red phosphors with the 450 nm blue LED chip. When upon the 20 mA bias driving current, the LED device demonstrates a bright warm-white light emission, which possesses a satisfactory color rendering index of 91, a low correlated color temperature of 4080 K, as well as a good luminous efficacy of 85.14 lm W −1 . The creative greenemitting CaY 2 HfGa(AlO 4 ) 3 :Ce 3+ garnet phosphor has a bright application prospect toward high-quality warm-white LED lighting.

A graphitic-C3N4 derivative containing heptazines merged with phenyls: synthesis, purification and application as a high-efficiency metal-free quasi-green phosphor for white LEDs

“…Though s-g-C 3 N 4 -Ph is a yellowish-green-emitting material, the results of its application in white LEDs suggest that it can provide a high-quality green light component for white light. Most of the reported green phosphors usually use rare-earth ions for green emission or sensitization, such as Ce 5 Si 3 O 12 N:Tb 3+ , 43 Ba 2 LiSi 7 AlN 12 :Eu 2+ , 44 RbLi(Li 3 SiO 4 ) 2 :Eu 2+ , 45 CaY 2 HfGa(AlO 4 ) 3 :Ce 3+ , 46 and CaY 2 ZrScAl 3 O 12 :Ce 3+ . 47 In comparison, s-g-C 3 N 4 -Ph is not only rare-earth-free but also metal-free, which makes it a cheap quasi-green phosphor for LEDs.…”

Pressure-sensitive Ce3+ photoluminescence in LiCaY5(BO3)6: high internal quantum yields and energy transfer to Tb3+

“…Such a red-shift for Ce 3+ is frequently seen, such as in the cases of BaLu 2 Si 3 O 10 : x Ce 3+ , 11 Ca 0.75−1.5 z Li 0.15 Al 0.75 Si 1.25 N 2.9 O 0.1 : z Ce 3+ , 27 Ca 1−2 x Ce x Li x AlSiN 3 , 28 LiY 9 (SiO 4 ) 6 O 2 :Ce 3+ , 29 NaSrY(BO 3 ) 2 :Ce 3+ , 30 and CaY 2 HfGa(AlO 4 ) 3 : Ce 3+ . 7 There is also Ce 3+ -to-Y 3+ replacement in the latter three cases. In the literature, this red-shift was usually explained using the following equation: , where Z is the anion charge, e is the electron charge, r is the radius of the d wave function, and R is the bond length between the central cation and its ligands.…”

“…Nowadays, the research interest in Ce 3+ -based phosphors remains high because Ce 3+ usually exhibits high-brightness and tunable emission (ranging from UV to red in different hosts). [7][8][9] The ground and excitation configurations are 4f 1 5d 0 and 4f 0 5d 1 , which result in intense absorption and emission bands due to the spin-and parity-allowed 4f-5d transition. In fact, the energy level of the 5d electron is susceptible to the surrounding crystal field, 7 thus the emission color could be tuned by modifying the coordination environment by applying chemical substitution or even physical pressure directly.…”

“…[7][8][9] The ground and excitation configurations are 4f 1 5d 0 and 4f 0 5d 1 , which result in intense absorption and emission bands due to the spin-and parity-allowed 4f-5d transition. In fact, the energy level of the 5d electron is susceptible to the surrounding crystal field, 7 thus the emission color could be tuned by modifying the coordination environment by applying chemical substitution or even physical pressure directly. Moreover, Ce 3+ is a frequently used sensitizer, transmitting partial excitation energy to co-activators.…”

Tuning of the thermal quenching performance of Bi3+-doped scheelite Ca(Mo/W)O4 solid solution phosphors

“…Ion-doped phosphor materials have been extensively employed in illumination and sensing, 3D displays, and biomedical fields in recent years. [1][2][3][4][5][6] Many phosphors, on the other hand, are severely limited in their applicability due to their inherent thermal quenching limitations. White light-emitting diodes (WLEDs) made of phosphors are currently extensively utilized in our everyday lives owing to their high longevity and green energy efficiency.…”