Strategies for Designing Antithermal‐Quenching Red Phosphors

Abstract

efficiency,low-energy consumption, long lifetime, and environmental compatibility, and so on. [1][2][3] The common w-LEDs devices are fabricated via two combination strategies: 1) blue LED chip and yellow phosphor; 2) nearultraviolet (n-UV) LED chip and tricolor phosphors. [4,5] No matter for which fabrication methods, the development of red phosphor is crucial to improve the lighting quality and tune corrected color temperature of w-LEDs. [6,7] To date, many researchers have focused on exploring highly efficient red phosphors. Although Eu 2+ -doped nitride phosphors such as CaAlSiN 3 :Eu 2+ and Sr 2 Si 5 N 8 :Eu 2+[8-10] show high quantum yield (QY > 90%) and high thermal quenching temperature (>600 K), the harsh preparation conditions (high pressure ≥ 0.9-2.5 MPa; high temperature ≥1700-200 °C) and deepred emission position (beyond 650 nm) limit the large-scale application in indoor lighting. Eu 3+ -doped inorganic compounds are typical red-emitting phosphors due to the (4f 6 ) 5 D 0 → (4f 6 ) 7 F J spin-and parity-forbidden transition, [11,12] but it is hardly utilized in w-LEDs applications owing to the linearly narrow excitation and emission. [13,14] Mn 4+ has been considered as the promising red-emitting activator Nowadays, red phosphor plays a key role in improving the lighting quality and color rendering index of phosphor-converted white light emitting diodes (w-LEDs). However, the development of thermally stable and highly efficient red phosphor is still a pivotal challenge. Herein, a new strategy to design antithermal-quenching red emission in Eu 3+ , Mn 4+ -codoped phosphors is proposed.

Thermally stable and highly efficient red-emitting Eu3+-doped Cs3GdGe3O9 phosphors for WLEDs: non-concentration quenching and negative thermal expansion

“…Figure 1c presents the lattice parameter ( a , b , c ) and volume ( V ) as a function of Eu 3+ content. It is clear that the cell parameter almost linearly increases as the Eu 3+ content increases from 0.1 to 1.0 and follows Vegard’s law 39 . Figure 1d shows the morphology and elemental distribution of CEGO, which displays a slight agglomeration of these phosphor particles.…”

Highly efficient yellow‐orange emission and superior thermal stability of Ba2YAl3Si2O12:Ce3+ for high‐power solid lighting

“…19,22 Meanwhile, high-power LED (>1 W/chip) is the mainstream, in which the thermal generation can be up to 423 K during the operating conditions. 5,6,23 At such high temperature, non-radiative relaxation of electronic excited states would be enhanced, resulting in the weakening of the emission intensity. Therefore, the thermal quenching is a vital index to evaluate the practicality of phosphors in w-LEDs.…”

“…Although a red‐shift from yellow to orange can be obtained via the solid solution design, reduced thermal stability and loss of luminescence efficiency are inevitable problems 19,22 . Meanwhile, high‐power LED (>1 W/chip) is the mainstream, in which the thermal generation can be up to 423 K during the operating conditions 5,6,23 . At such high temperature, non‐radiative relaxation of electronic excited states would be enhanced, resulting in the weakening of the emission intensity.…”

Efficient red and broadband near‐infrared luminescence in Mn2+/Yb3+‐doped phosphate phosphor

“…The exploration of energy‐saving and environment‐friendly technologies and the development of advanced functional materials are expected to alleviate this crisis 1‐4 . Recently, pc‐WLEDs have attracted extensive attention as a new generation of solid‐state lighting equipment, which is displacing the traditional incandescent, mercury, and fluorescent lamps due to their advantages of low energy consumption, high efficiency, environment friendly, and long service time 5‐11 . Currently, the main commercial WLEDs are to combine a 460 nm emitting LED chip and a yellow‐emitting YAG:Ce 3+ phosphor 12‐16 .…”

“…[1][2][3][4] Recently, pc-WLEDs have attracted extensive attention as a new generation of solid-state lighting equipment, which is displacing the traditional incandescent, mercury, and fluorescent lamps due to their advantages of low energy consumption, high efficiency, environment friendly, and long service time. [5][6][7][8][9][10][11] Currently, the main commercial WLEDs are to combine a 460 nm emitting LED chip and a yellow-emitting YAG:Ce 3+ phosphor. [12][13][14][15][16] However, this combination suffers from the disadvantages of high correlated color temperature (CCT) and low color rendering index (Ra) because of insufficient red light components.…”