Warm WLEDs Research Articles

A double perovskite-based red-emitting phosphor with robust thermal stability for warm WLEDs

Red-emitting Ba2YSbO6:Eu3+ phosphors with double perovskite structure have been prepared by solid-state method. Phase structures, photoluminescence properties, and thermal stability performances have been investigated in detail. The prepared phosphors reveal a cubic phase with the space group of Fm-3m. They exhibit a doughty red emission band at 612 nm ascribed to the Eu3+:5D0→7F2 transition under 393 and 465 nm excitation. The samples have high concentration quenching property with the optimal concentration reached to 70 mol%, deriving from the quadrupole-quadrupole interaction. Additionally, the Ba2YSbO6:Eu3+ phosphors demonstrate robust thermal performance with the emission intensity retaining 78.8% at 423 K of that at 303 K. Ultimately, the phosphor-converted LED device is fabricated by combining the red-emitting Ba2YSbO6:Eu3+ phosphor and YAG:Ce3+ yellow ones to a blue chip (460 nm), which exhibits a warm white light with color rendering index(CRI) of 80.8 and correlated color temperature (CCT) of 5184 K.

Color tuning of β-Ca3(PO4)2-type phosphor with enhanced quantum efficiency via self-charge compensation for healthy and warm solid state lighting application

Phosphor with high efficiency and tunable photoluminescence is critical to solid state lighting device. Herein, three β-Ca3(PO4)2-type phosphors with improvement of quantum efficiency and tunable emission color were synthesized through the self-charge compensation method via the incorporation of Na+ or K+. The quantum efficiency and emission intensity were increased by 2.81 and 1.99 times at most due to the reduction of Eu3+ to Eu2+ in Ca10Na(PO4)7:0.01Eu2+, which was ascribed to the achievement of charge balance and cavity neutralization in Na(4) site after the incorporation of Na+ in the neighboring Ca(1), Ca(2) and Ca(3) sites. Tunable emission colors from near white to green were realized owing to the change of occupation ratio of Eu2+ at Ca(1), Ca(2) and Ca(3) sites relative to Na(4) site. Moreover, this method was applied into the Ca10-yK1+y(PO4)7:0.01Eu2+ and 0.1Ca9Y(PO4)7–0.9Ca10-zNa1+z(PO4)7:0.01Eu2+, 0.22Mn2+ systems to verify the practicability of self-charge compensation. The quantum efficiencies of the two kinds of systems were increased by 1.66 and 1.28 times, respectively, along with the decrease of blue light ratio significantly. Additionally, no blue light hazard and warm WLEDs was fabricated via the modified single-phase full visible emission 0.1Ca9Y(PO4)7–0.9Ca9.9Na1.1(PO4)7:0.01Eu2+, 0.22Mn2+ phosphor, which exhibited an excellent color rendering index of 92.9 at a correlated color temperature of 3887 K. This work illustrated that the universal self-charge compensation method could efficiently improve the multifaceted properties of phosphor to meet the needs of modern lighting.

Warm white-light phosphor based on a single-phase of Ag+/Eu3+/Zn2+ loading SOD zeolites with application to white LEDs

Single-phase white-light phosphors are still much preferred materials for easily manufacturing white LEDs with excellent properties such as improved stability and color reproducibility. Herein, we report a new white emitting phosphor upon the incorporation of Ag+ into the Zn2+ containing SOD zeolites and achieve a series of warm white emitting phosphors by an addition of Eu3+. Under the ultraviolet excitation of 395 nm, the material of Ag10Eu displays the white light with CIE chromaticity coordinate of (0.33, 0.34), the quantum efficiency of 22%, appropriate CRI of 85 and CCT value of 5838 K. In addition, such material with the advantages including appropriate excitation wavelengths, good emission performance and high thermal stability is highly desirable for WLEDs. The as-fabricated warm WLEDs show the appropriate CIE chromaticity coordinates of (0.37, 0.35), with a lower CCT of 4041K, a higher Ra of 87, which match with the traditional incandescent light quality benchmarks. This new single-component warm white emitting phosphors point interesting applications for UV-LED chip excited white LEDs.

Luminescence properties and energy transfer of LaAl2.03(B4O10)O0.54: Dy3+, Eu3+ phosphors

A sequence of LaAl2.03(B4O10)O0.54: Dy3+, Eu3+ phosphors were produced by sol-gel reaction method. A number of properties such as phase composition, crystal structure, luminescence performance, lifetime decay curves and mechanism of energy transfer were discussed. Characteristic emission pertain to Dy3+ and Eu3+ ions were observed in its emission spectrum when excited under a wavelength of 349 nm. By comparing the emission spectrum and the fluorescence lifetime decay curves of LaAl2.03(B4O10)O0.54: 0.06Dy3+, yEu3+ phosphors, it can bear out that the energy transfer among Dy3+ ions and Eu3+ ions was existed, and the mechanism of energy transfer was proved to dipole-dipole interaction. The color of these samples can change from green to orange with the increase of concentration of Eu3+ ions concentration, and its correlated color temperature is improved. These results show that the LaAl2.03(B4O10)O0.54: Dy3+, Eu3+ phosphors can be applied for warm WLEDs under near ultraviolet (n-UV).

Efficient and stable Sr3Eu2B4O12 red phosphor benefiting from low symmetry and distorted local environment.

The development of suitable red phosphors to obtain improved white color stands a good chance to serve in the new generation of white light-emitting diodes. Owing to multi-elements via doping and oxidation of reduced valence state of lanthanide or transition metal ions, most of the reported phosphors usually suffer from complex synthetic processes and unstable color of the lighting industry cycle. In this work, we present a new red emitting and stable Sr3Eu2B4O12 phosphor with regard to its special structure. It crystallizes as an orthorhombic cell, with Sr and Eu atoms co-occupying three different lattice sites in the space group of Pnma (no. 62). It is proposed that the long bond distance between activators minimizes the content quenching, while the high disorder of location restricts the thermal quenching. This phosphor emits bright red light with good color purity under UV excitation, with the luminescence intensity and quantum yield tunable via the fabrication temperature. Through a preliminary optimization of the synthesis process, the Sr3Eu2B4O12 phosphor prepared at 1250 °C has high quantum yields of about 94.7% and excellent thermal stability of 85.6% intensity retention at 150 °C relative to the initial value at room temperature. The calculated Judd-Ofelt intensity parameters (Ω2, Ω4) further clarified that the Eu3+ site in Sr3Eu2B4O12 had lower symmetry without an inversion center, and more distorted local environment and structural rigidity of the host, predicting excellent thermal stability. Finally, a warm pc-WLED device has been produced by mixing as-prepared Sr3Eu2B4O12 powders and commercial BaMgAl10O17:Eu2+ and (Sr, Ba)2SiO4:Eu2+ phosphors, which exhibits a high color rendering index (Ra = 83.4) along with a color temperature at around 4102 K. The present work indicates that the Sr3Eu2B4O12 phosphor is an efficient red component with excellent thermal stability for white-light production of near-UV-excited w-LEDs.

Co-precipitation synthesis, luminescent properties and application in warm WLEDs of Na3GaF6:Mn4+ red phosphor

The Na3GaF6:Mn4+ phosphor was prepared by co-precipitation method in our work. The structure, morphology and composition have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometers (EDS), respectively. The Na3GaF6:Mn4+ produces sharp red emission when excited by blue light at 465 nm. The effect of reaction parameters on its morphology and luminescence properties was researched. In addition, the crystal-field strength and emission mechanism of Mn4+ in Na3GaF6 were analyzed. Moreover, the concentration quenching mechanism was also investigated. Finally, using Na3GaF6:Mn4+ as red material, a warm WLED with low color temperature (3670 K), high color rendering index (Ra = 82) and luminous efficiency of 123 lm/W was achieved. Above results suggest that Na3GaF6:Mn4+ has latent application value in warm WLEDs.

Effects of graphene quantum dots coating on the luminescence properties of K2SiF6:Mn4+ red-emitting phosphors

A series of K2SiF6:0.06Mn4+@ GQDs y mg/mol (KSF: K2SiF6, GQDs: graphene quantum dots) red-emitting phosphors were prepared with a simple coating method. Experimental results show that the KSF:0.06Mn4+@ GQDs y mg/mol has broad excitation bands in blue region and strong emission line bands in red region with the strongest peak at ~ 630 nm. Enhanced luminescence intensity and thermal stability induced by GQD coating are observed: (i) the integrated intensity of KSF:0.06Mn4+@ GQDs 5mg/mol is 1.32 times of that of KSF:0.06Mn4+, (ii) the integrated intensities of KSF:0.06Mn4+@ GQDs 5mg/mol at 120 and 180 °C are 1.57 and 1.26 times of that at 25 °C. Through temperature-dependent behavior measurement and stability test, it can distinctly learn that KSF:0.06Mn4+@GQDs 5 mg/mol exhibits exceptional thermal stability as well as color stability under LED-operating temperature conditions, which implies that the sample has potential applications for blue light-based warm W-LEDs.

Rapid and room temperature synthesis of MAPb1−xSnxBr3−2xCl2x perovskite quantum dots with enhanced lifetime in warm WLEDs: A step towards environmental friendly perovskite light harvester

In this work, a facile approach to develop nontoxic CH3NH3PbBr3 perovskite quantum dots (PQDs) by substituting tin (Sn2+) ion instead of lead (Pb2+) ion and chloride (Cl−) ion instead of bromide (Br−) ion has been reported. Synchronized cation and anion substitution in CH3NH3Pb1−xSnxBr3−2xCl2x PQDs has resulted in commercial-friendly properties like fine-tuning of bandgap, shifting of color emission from green to cyan region (523 nm–490 nm), enhancing structural stability, excitonic lifetime, and color gamut. Presence of Sn2+ cations in +2 state, Cl− anions in −1 state, and ion exchange was confirmed from various spectroscopic and morphological analyses. Photoluminescence quantum yield (PLQY) for unsubstituted CH3NH3PbBr3 was observed as 97.50% and it is reduced to >50% for 15% SnCl2 substituted CH3NH3PbBr3 PQDs because of the presence of defect-related nonradioactive recombination centres while cation and anion changeover. Warm white LED prototype with 123% color gamut encircling as per National Television System Committee Standard was achieved using as prepared CH3NH3Pb1−xSnxBr3−2xCl2x PQDs and commercial red phosphor on the blue LED chip. The inflated colour-gamut, promising PLQY, and slender FWHM of as-synthesized CH3NH3Pb1−xSnxBr3−2xCl2x PQDs illustrate great prospect to explore their utilization in display applications. Reduction in toxicity in perovskite material was confirmed by the biological study.

Green emitting Ba1.5Lu1.5Al3.5Si1.5O12: Ce3+ phosphor with high thermal emission stability for warm WLEDs and FEDs

By hetero-valence substituting Ba2+-Si4+ for Lu3+-Al3+ pair in Lu3Al5O12: Ce3+, a new green phosphor Ba1.5Lu1.5Al3.5Si1.5O12: Ce3+ (BLAS: Ce3+) has been obtained. It crystallizes in garnet structure with space group Ia-3d (230). In the structure, Ba2+ ions are incorporated into both dodecahedral Lu3+ and octahedral Al3+ sites while Si4+ ions only occupy tetrahedral Al3+ sites. Under the blue light irradiation of 450 nm, an intense green light peaking at 520 nm was observed and the PL spectrum can be fitted in two Gaussian components, due to the crystal field splitting of Ce3+ 5d states under D2 symmetry constrains. The optical doping concentration of BLAS: Ce3+ is 6% mol, of which the IQE and EQE are 89.1% and 51.8%, respectively. Furthermore, this sample exhibits an extremely good thermal stability, i.e. the integrated emission intensity is still more than 90% of the initial intensity at 480 K. Then, a w-LED device was fabricated from this new green phosphor BLAS: Ce3+ and commercial red phosphor (Ca,Sr)AlSiN3: Eu2+, which shows a quite high color rendering (Ra = 88.2) and a relatively low color temperature 4772 K. Besides, the phosphor exhibits a stable chromaticity under different acceleration voltages. The phosphor may be promising material for the development of solid-state lighting and display systems.

Bio-mediated Combustion Synthesis and Color Characteristic Studies of Y2O3:Tm3+ Nanoscale Superstructures

Mimosa pudica(MP) plant extract was used to prepare Y2O3:Tm3+ (1-11mol %) nanoscale superstructure with nitrate source as precursors. The samples were characterized by advanced characterization techniques. The PXRD peaks indicates crystalline, no impurity peaks were present with body centre cubic structure of Y2O3. Photoluminescence emission spectra shows blue color emission at 358 nm excitation wavelength. The major peak of Tm3+ was at 453 nm and two very weak peaks were observed at ∼ 474 nm attributed to the transitions of 1D2 → 3 F4 and 1G4 → 3H6, res. The calculated color co-ordinates were matches to the NTSC blue color. Correlated color temperature was ∼ 4000 K. So the Y2O3:Tm3+ nanophosphor could be used for blue component in the warm WLED and SSL devices.

Single 395 nm excitation warm WLED with a luminous efficiency of 10486 lm/W and a color rendering index of 907

A blue Sr5(PO4)3Cl:Eu2+ phosphor was synthesized by the solid state reaction method. Higher luminescence intensity was observed by increasing the NH4Cl content to twice the stoichiometric ratio. Then a near UV excited warm white LED was fabricated by using an InGaN/GaN chip (395 nm) coated with tricolor phosphors, including (Sr,Ca)AlSiN3: Eu2+ (red), (Ba,Sr)2SiO4: Eu2+ (green), and Sr5(PO4)3Cl:Eu2+ (blue). Moreover, a two-layer LED fabrication structure was designed to weaken the secondary absorption of blue emission by the red and green phosphors. A good luminescence performance was achieved with the correlated color temperature (CCT) of 3150 K, a color rendering index (CRI) of 90.7, CIE chromatic coordinates of (0.4354, 0.4196), and luminous efficiency of 104.86lm/W.

Novel luminescence enhancement and splitting of excitation and emission bands of Na2SiF6:Mn4+,Li+ phosphors induced by Li+ co-doping

In this paper, a series of novel Na2SiF6:Mn4+,Li+ (NSF:0.05Mn4+, xLi+) phosphors were prepared with the cation exchange method. Some novel luminescent properties inducing by doping Li+ were observed: First, the striking thing is that the excitation (PLE) & emission (PL) intensities of Li+-doped sample (NSF:0.05Mn4+, 0.08Li+) are 11.7 times higher than those of NSF:0.05Mn4+; Second, when the concentration of Li+≥ 20%: (a) transition of 4A2g→4T2g in excitation band and zero phonon line (ZPL), s-v4 in emission band are all split into two peaks, respectively; (b) the peak intensities of as-v6, ZPL, v6 and v4 in emission band are almost the same. The mechanism of these phenomena was discussed. The color purity, crystal-field, nephelauxetic effect, the critical distance and the multipolar interaction for the samples were determined. Besides, the optimal sample (NSF:0.05Mn4+, 0.08Li+) has an excellent QY, which is as high as 99.83%. Good warm white light with low correlated color temperature (CCT = 4362 K) and high color rendering index (Ra = 88.5) was obtained from prototype WLEDs using the mixing phosphors of the optimal sample and YAG:Ce3+ on InGaN chip under a 20 mA drive current, making the optimal sample has potential application for blue light-based warm WLEDs.

Significant enhancement and broadening of excitation bands of K2SiF6:Mn4+, NH4+ phosphors induced by NH4+

A series of K2SiF6: 0.06Mn4+, xNH4+ red emitting phosphors were prepared via the cation exchange method. Significant enhancement of excitation and emission bands and strongly broadening of excitation bands induced by NH4+ were observed: (a) Intensities of PLE and PL are not only enhanced obviously, but also PLE is significantly widened. (b) The relative intensity of 4A2→4T1 peak is greatly increased. (c) The sample doping with NH4+ has ZPL, while the sample without doping of NH4+ has no ZPL. Internal QY of the K2SiF6:0.06Mn4+, 0.05NH4+ is 98%. The mechanisms of the enhancement are discussed and proposed. Finally, warm white light with good luminescence efficiency (122 lm W−1), low correlated color temperature (CCT = 4146 K) and high color rendering index (Ra = 85.9 and R9 = 81) was obtained from the prototype WLEDs fabricated by using the optimal sample, indicating it has potential application for blue light-based warm WLEDs.

Review—Mn4+-Activated Red and Deep Red-Emitting Phosphors

Mn4+-activated phosphors are a new class of non-rare earth phosphors and are alternative to commercial Eu2+-activated nitride/oxynitride phosphors with growing interest in various applications. In this review article, the structural and photoluminescence (PL) properties of various Mn4+-activated phosphors have been discussed. The host materials considered here can be roughly classified into five groups; fluorides, oxides, oxyfluorides, and two fluorine compounds. Phosphors of each group can also be classified into totally eleven subgroups from their different PL spectral features, e.g., whether an appearance of the zero-phonon line (ZPL) emission peak or not. The ZPL emission and absorption energies of the Mn4+ ions have been determined from the PL and PL excitation spectra using the Franck−Condon analysis method within the configurational-coordinate (CC) model. These results are used to obtain reliable phosphor parameters, i.e., the crystal-field (Dq) and Racah parameters (B and C), of the Mn4+ ions in the various host materials. The PL intensity vs temperature data, together with those of the luminescence lifetimes, are modeled on the basis of the CC model, and an excellent agreement has been achieved if not only the optical phonon but also the acoustic phonon contribution is taken into consideration in the conventional thermal quenching model. Effects of the hydrostatic pressure and dopant concentration on the PL spectral features are also discussed. Finally, key properties of the Mn4+-activated phosphors are discussed for use of such red and deep red-emitting phosphor systems in warm w-LED and indoor plant cultivation applications.

Synthesis of a novel red phosphor K2xBa1-xTiF6:Mn4+ and its enhanced luminescence performance, thermal stability and waterproofness

Investigation of efficient red phosphors is highly desired for the development of novel warm white light emitting diodes. In this paper, through a facile method, we first introduce K+ to replace Ba2+ to synthesize a novel K2xBa1-xTiF6:Mn4+ solid solution phosphor with high luminous efficiency, high thermal stability and good waterproofness. Significantly, compared with two best luminescence performance samples (BaTiF6:0.006Mn4+ and K0.070Ba0.965TiF6:0.018Mn4+), the luminescence intensity of K0.070Ba0.965TiF6:0.018Mn4+ is increased by 6 times, the quantum efficiency is improved from 40% to 75% and the activation energy of thermal quenching is improved to 0.940 eV from 0.628 eV. Remarkably, the waterproofness is improved by 45% than traditional red phosphor K2TiF6:Mn4+ after being immersed in water for 150 min. Moreover, a high-performance WLED with low correlated color temperature (CCT = 3930 K), high color rendering index (Ra = 90.3) and luminous efficacy of 105 lm/W is achieved by employing blue-emitting GaN chip, yellow-emitting YAG:Ce3+ phosphor and red-emitting K0.070Ba0.965TiF6:Mn4+ phosphor. These results reveal that introduced suitable cation may have a positive effect on luminescent properties of Mn4+ activated fluoride phosphors, which is a helpful tool for their performance improvement, and K0.070Ba0.965TiF6:Mn4+ presents a good luminescent property and may be a potential candidate for high-performance warm WLED.

A promising thermally robust blue-green Li-α-sialon:Ce3+ for ultraviolet LED-driven white LEDs

Rare earth ions doped (oxy)nitride phosphors have been shown great potentials for the use as down-conversion luminescent materials in white light-emitting diodes (wLEDs). To realize super-high color rendering and high efficiency wLEDs driven by a 405 nm LED chip, a blue-green phosphor with high thermal stability and quantum efficiency is required. In this work, we reported an interesting blue-green emitting Li-α-sialon:Ce3+ (LimSi12-m-nAlm+nOnN16-n:Ce3+) that has a high external quantum efficiency of 53.5% and a small luminescence intensity reduction of 6.1% at 423 K. A variety of analytic techniques, such as X-ray diffraction (XRD), photoluminescence (PL) spectra, X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and nuclear magnetic resonance (NMR) spectra, were used to clarify the relation between photoluminescent properties and local coordination environments. It showed that the emission color and luminescence intensity of Li-α-sialon:Ce3+ could be controlled by the microstructure tailoring. A warm wLED was demonstrated by pumping the phosphor with the blend of Li-α-sialon:Ce3+, β-sialon:Ce3+ and CaAlSiN3:Eu2+ by a 405 nm LED chip, which has the color temperature, color rendering index and luminous efficacy of 2390 K, 92.2 and 26.05 lm/W under a driven current of 20 mA. Our results indicate that Li-α-sialon:Ce3+ is a promising thermally robust blue-green phosphor for ultraviolet LED-driven wLEDs.

Synthesis and photoluminescence of Mn4+ in M4Al14O25 (M = Sr or Mg) compounds as red-light phosphors for white LED

Red-light-emitting phosphors Mn4+-doped M4Al14O25 (M = Sr or Mg) were synthesized by solid-state reaction at 1400 °C in air, and their luminescent properties were initially investigated for their applications in warm white-light-diodes (W-LEDs). The excitation spectra of Mn4+-doped M4Al14O25 (M = Sr or Mg) showed that those phosphors were efficiently excited by near ultraviolet (UV) or blue LED chips, and those phosphors exhibited deep red emission band around 650 nm arising from the spin-forbidden 2E → 4A2 transition of Mn4+. The energy transfer mechanism in Mn4+-doped Mg4Al14O25 phosphor was found to be the electric dipole-dipole interaction and the critical distance of energy transfer between the Mn4+ ions was obtained to be about 1.384 nm. The Commission International de L’Eclairage (CIE) chromaticity coordinates of 0.5at.% Mn4+-doped Mg4Al14O25 were (0.631, 0.252). The temperature-dependent luminescence indicated Mn4+-doped M4Al14O25 phosphor was poor thermal-stable. Further work related to improve its thermal stability need be executed for Mn4+-doped M4Al14O25 (M = Sr or Mg) as a promising candidate of red-component for warm W-LEDs.

Color tunable and energy transfer mechanism of Dy3+ and Eu3+ rare earth ions activated NaCaBi2(PO4)3 eulytite type phosphor for NUV excitable warm white light emitting diodes

The Dy3+ and Eu3+ individually doped and co-doped NaCaBi2-x(PO4)3 (hereafter called as NCBP) eulytite type phosphors were prepared by solid state reaction method with different doping concentrations. The phase formation and the morphological studies were analyzed using the PXRD data and SEM images respectively. The structure of the NCBP host was modeled by VESTA software using the results obtained from the Rietveld refinement analysis. The band gap of the NCBP host and the Dy3+, Eu3+ ions doped /co-doped NCBP phosphors were estimated from the DRS measurements. The luminescence spectra and decay curves of the phosphors were analyzed. The energy transfer mechanism between the Dy3+ and the Eu3+ ions in the NCBP:0.07Dy3+,xEu3+ was investigated. The CIE chromaticity co-ordinates of the NCBP:xDy3+ were located in the cold (5695 K) and neutral white region (4894 K). For NCBP:xEu3+, these co-ordinates lie in the reddish orange region with low CCT values (1622 to 1671 K). By changing the Eu3+ content in the co-doped phosphors and exciting at suitable wavelengths (350, 362 and 395 nm), the emission color could be tuned from neutral white (4661 K) to warm white (2725 K) to reddish orange light (1756 K). These results suggest that the co-doped phosphors might be potential color tunable candidates for the NUV excitable warm WLEDs.

Highly efficient red-emitting Ca2YSbO6:Eu3+ double perovskite phosphors for warm WLEDs.

Highly efficient red-emitting Eu3+-doped double perovskite Ca2YSbO6 phosphors have been successfully prepared by the traditional high-temperature solid state method. The phase purity, photoluminescence and decay properties as a function of the Eu3+ concentration have been investigated in detail. The XRD results demonstrate that all of the obtained phosphors can be assigned to a pure monoclinic structure. Upon 464 nm excitation, a strong red emission situated at 614 nm (5D0–7F2) indicates that Eu3+ ions occupy a site with low symmetry. The quenching concentration of Eu3+ ions reaches as high as 70 mol% and the quenching mechanism is discussed. Especially, the prepared phosphor exhibits a high quantum efficiency of 92.1% and superior thermal stability, with PL intensity at 423 K up to 81.6% of that at room temperature. Moreover, a warm white light with a correlated color temperature of 4720 K and a color rendering index of 82.6 is achieved by fabricating a Ca2YSbO6:Eu3+ phosphor in a 460 nm blue-InGaN chip together with the commercial Y3Al5O12:Ce3+ yellow phosphor.

Epitaxial growth via anti-solvent-induced deposition towards a highly efficient and stable Mn4+ doped fluoride red phosphor for application in warm WLEDs

We report epitaxial growth via simple ethanol-induced deposition to enhance the luminescence and moisture resistance of K2SiF6:Mn4+.