Highly efficient non-rare-earth red emitting phosphor for warm white light-emitting diodes

Abstract

Mn 4 þ -activated fluoride compounds, as an alternative to commercial (oxy)nitride phosphors, are emerging as a new class of non-rare-earth red phosphors for high-efficacy warm white LEDs. Currently, it remains a challenge to synthesize these phosphors with high photoluminescence quantum yields through a convenient chemical route. Herein we propose a general but convenient strategy based on efficient cation exchange reaction, which had been originally regarded only effective in synthesizing nano-sized materials before, for the synthesis of Mn 4 þ -activated fluoride microcrystals such as K 2 TiF 6 , K 2 SiF 6 , NaGdF 4 and NaYF 4 . Particularly we achieve a photoluminescence quantum yield as high as 98% for K 2 TiF 6 :Mn 4 þ . By employing it as red phosphor, we fabricate a high-performance white LED with low correlated colour temperature (3,556 K), high-colour-rendering index (R a ¼ 81) and luminous efficacy of 116 lm W À 1 . These findings show great promise of K 2 TiF 6 :Mn 4 þ as a commercial red phosphor in warm white LEDs, and open up new avenues for the exploration of novel non-rare-earth red emitting phosphors.

Photoluminescence properties of a novel red fluoride K2LiGaF6:Mn4+nanophosphor

“…Some of them show high quantum efficiency, thermal stability against quenching and so on. 46 Recently, we had reported a red phosphor K 2 LiAlF 6 :Mn 4+ , 47 which belongs to the elpasolite group of materials with a double perovskite structure. Though it has excellent thermal quenching behavior, the luminescence intensity is still not high enough.…”

Synthesis and photoluminescence properties of Eu3+-activated LiCa3ZnV3O12white-emitting phosphors

“…[11][12][13][14] Nowadays, the widely used WLEDs are fabricated by coating YAG:Ce 3+ yellow phosphors on InGaN blue LED chips, however these WLEDs commonly suffer from high correlated color temperature (CCT) and low color rendering index (CRI) owing to the lack of a red component, limiting their applications in indoor lighting. [15][16][17][18][19][20][21] On the other hand, the WLEDs made by multiple-emitting phosphors also have some drawbacks, such as intrinsic color balance, device complication and high cost. [22][23][24][25][26][27][28] Compared to former two approaches, the latest approach is highly promising, due to its high luminescence efficiency, color repeatability, and low manufacturing costs.…”

Using DFT Methods to Study Activators in Optical Materials

“…For example, new efficient red phosphors with suitable emission wavelengths are highly desirable for producing warm white light from LEDs; [21][22][23]6,14 scintillators with improved energy resolutions are sought for gamma-ray spectroscopy. 24 Theoretical calculations can be useful for searching for new materials and optimizing existing materials.…”