Highly Efficient and Stable Narrow-Band Red Phosphor Cs₂SiF₆:Mn⁴⁺ for High-Power Warm White LED Applications

Abstract

Due to the unique narrow-band red emission and broadband blue light excitation, as well as milder synthesis conditions, Mn 4+ ion activated fluoride red phosphors show great promise for white light emitting diode (W-LED) applications. However, as the Mn 4+ emission belongs to a spin-forbidden transition ( 2 E g → 4 A 2 ), it is a fundamental challenge to synthesize these phosphors with a high external quantum efficiency (EQE) above 60%. Herein, a highly efficient and thermally stable red fluoride phosphor, Cs 2 SiF 6 :Mn 4+ , with a high internal quantum efficiency (IQE) of 89% and ultrahigh EQE of 71% is demonstrated. Furthermore, nearly 95% of the room-temperature IQE and EQE are maintained at 150 °C. The static and dynamic spectral measurements, as well as density functional theory (DFT) calculations, show that the excellent performance of Cs 2 SiF 6 :Mn 4+ is due to the Mn 4+ ions being evenly distributed in the host lattice Cs 2 SiF 6 . By employing Cs 2 SiF 6 :Mn 4+ as a red light component, stable 10 W high-power warm W-LEDs with a luminous efficiency of ∼110 lm/W could be obtained. These findings indicate that red phosphor Cs 2 SiF 6 :Mn 4+ may be a highly suitable candidate for fabricating high-performance high-power warm white LEDs.

Novel Mn4+-activated LiLaMgWO6far-red emitting phosphors: high photoluminescence efficiency, good thermal stability, and potential applications in plant cultivation LEDs

“…[22][23][24][25][26][27][28][29][30][31][32] Recently, it was reported that Mn 4+ ions with a far-red emission of around 710 nm can also be used for plant cultivation LEDs because the emission range due to the 2 E g / 4 A 2g transition was in accordance with the absorption band of phytochrome P FR (centers at 730 nm). 33 Moreover, the Mn 4+ ion can be excited by both blue and near-ultraviolet (NUV) LED chips and exhibits wide absorption bands, which broaden the application eld.…”

Insight into a novel rare‐earth‐free red‐emitting phosphor Li3Mg2NbO6:Mn4+: Structure and luminescence properties

“…11,14 Owing to the advantages in this field, Mn 4+ -doped red phosphors have drawn much attention. 20 Nevertheless, fluoride phosphors not only suffer from instability under moisture environment but also endanger the environment usually due to the employed toxic HF solution in the synthesis process. [15][16][17] Among Mn 4+ -doped red phosphors, fluoride compounds usually exhibit efficient sharp emission peaking at ~630 nm.…”

“…[15][16][17] Among Mn 4+ -doped red phosphors, fluoride compounds usually exhibit efficient sharp emission peaking at ~630 nm. Thus, warm WLED can be reached by employing Mn 4+ -activated fluoride phosphors plus YAG:Ce 3+ , which has been demonstrated in many cases, including K 2 SiF 6 :Mn 4+ , 16 20 Nevertheless, fluoride phosphors not only suffer from instability under moisture environment but also endanger the environment usually due to the employed toxic HF solution in the synthesis process. These problems should be further concerned.…”

New Insight for Luminescence Tuning Based on Interstitial sites Occupation of Eu2+ in Sr3Al2−xSixO5−xNxCl2 (x = 0–0.4)

“…Currently, the commercial fabrications of w‐LEDs usually employ the strategy that combines InGaN blue chips and the Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce 3+ ) yellow phosphor . However, the well‐known shortcomings are the high color temperature (CCT, > 6000 K) and low color rendering index (CRI, R a < 80), caused by the emission deficiency in the red region . These shortcomings hinder the residential application of the w‐LEDs in daily life.…”