Structure and Luminescence Properties of Mn⁴⁺-Activated K₃TaO₂F₄ Red Phosphor for White LEDs

Abstract

A novel red oxyfluoride phosphor K3TaO2F4:Mn4+ has been prepared by a simple two-step synthesis method. The structure, composition, and luminescence properties of K3TaO2F4:Mn4+ phosphors were investigated and discussed in detail. The real structure of K3TaO2F4 was carefully studied through X-ray powder diffraction data Rietveld refinement. K3TaO2F4 holds a D 4h group symmetry [TaO2F4]3– octahedron with the oxygen occupying the para-position. Under ultraviolet (UV) and blue light excitation, K3TaO2F4:Mn4+ phosphor emits a narrow band red emission peaking at 630 nm. High-performance warm white-light-emitting diodes (WLEDs) were fabricated using a blue LED chip, YAG:Ce3+ yellow phosphor, and K3TaO2F4:Mn4+ red phosphor. This device exhibits high color quality (CCT = 3488 K, Ra = 93.0, R9 = 90.0), which indicates that Mn4+-doped K3TaO2F4 would be a promising red phosphor for WLED applications.

A Reverse Strategy to Restore the Moisture‐deteriorated Luminescence Properties and Improve the Humidity Resistance of Mn4+‐doped Fluoride Phosphors

“…In recent years, Mn 4 + doped fluoride phosphors have attracted widespread attention in the fields of liquid crystal display (LCD) [1] and solid-state lighting (SSL). [2] So far, a series of Mn 4 + -doped fluoride red-emitting phosphors, such as A 2 XF 6 : Mn 4 + (A = NH 4 , Li, Na, K, Rb and Cs; X = Si, Ti, Ge, Sn, Zr and Hf), [3][4][5][6] BXF 6 (6H 2 O) : Mn 4 + (B = Ba and Zn), [7][8][9][10] A 3 MF 6 : Mn 4 + (M = Al, Ga and Sc), [1,[11][12][13] A 2 NF 7 : Mn 4 + (N = Ta and Nb), [14,15] A 2 NO x F 6-x : Mn 4 + (x = 1, N = Ta and Nb; x = 2, N = W and Mo) [16][17][18][19] and A 3 XF 7 : Mn 4 + [20] has been reported. Unfortunately, although fluoride phosphors with a narrow emission at around 630 nm exhibit unique luminescence performance under blue light excitation, the deterioration of luminescent properties as a result of obvious hydrolysis has limited their large-scale application.…”

Orange‐Red‐emitting Ca9Gd(PO4)7:Eu3+ Phosphors: Judd‐Ofelt Analysis and Investigation on the Thermal Stability, Quantum Efficiency for WLED

“…A typical WLED was simply fabricated by combining a 460 nm blue InGaN chip with a cerium(III)‐doped yttrium aluminum garnet yellow phosphor, Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce 3+ ) [7–11] . However, due to the shortage of red spectral component, this type of LED has a low‐quality color rendering index (R a =70–80) and a high correlated color temperature (CCT=4000–7500 K) [7,12–15] . Thus, using yellow‐emitting phosphors with a better red contribution to coat is prevalently used for obtaining a high‐R a white light and an efficient CCT.…”

A Novel Red-Emitting Na2NbOF5:Mn4+ Phosphor with Ultrahigh Color Purity for Warm White Lighting and Wide-Gamut Backlight Displays

“…The oxyfluoride compounds are regarded as succedaneous hosts for Mn 4+ substitution because Mn 4+ in some oxyfluoride hosts also presents parallel photoluminescent (PL) properties with Mn 4+ -activated fluoride phosphors. More interestingly, the oxyfluoride compounds may induce Mn 4+ to exhibit excellent luminescence properties owing to distorted octahedral sites and Fand O 2mixed ligands [27]. Hence, the exploration for new Mn 4+ -doped red-emitting phosphors based on oxyfluorides is of great significance.…”