Phosphor-converted White Light-emitting Diodes Research Articles

Cs2MnCl4:Eu2+: A Near-Violet Light-Triggered Single-Component White Light Emitter.

Single-component white-light luminescent materials are considered an economical and facile choice for phosphor-converted white light-emitting diodes (pc-WLEDs). Here, a new single-component white-light-emitting material Cs2MnCl4:Eu2+ based on the combination of a lead-free halide structure and a rare-earth ion is first reported. Benefiting from the smart dilution-sensitization design strategy, white light composed of dual broad emission originating from Eu2+ (blue light, 444 nm, 4f65d1 → 4f7) and Mn2+ (yellow light, 566 nm, 4T1g → 6A1g) was successfully realized under near-ultraviolet light (404 nm) radiation with a high photoluminescence quantum yield of 66%. Based on the single-source Cs2MnCl4:Eu2+ phosphor, a pc-WLEDs device with "eye-friendly" white light production was successfully fabricated. The pc-WLEDs exhibit suitable color coordinates of (0.3294, 0.2746) and a high color rendering index of 82.3, demonstrating the potential in the future health-conscious illumination application by reducing the risk of eye strain and high-energy blue-light damage. This work achieves a new single-component white-light-emitting Mn-based halide phosphor and provides a new path for the design of single-component white light sources in Mn-based halides.

Climatically Accelerated Material Processes Determining the Long-Term Reliability of Light-Emitting Diodes.

LEDs (Light-Emitting Diodes) are widely applied not only in decorative illumination but also in everyday lighting in buildings, flats, public areas, and automotive fields. These application areas often mean harsh environments, for example, regarding the humidity content of the surrounding air: besides outdoor and automotive illumination, even the household use cases (kitchen, bathroom, cellar) may represent extreme temperature and humidity variations (often reaching relative humidity levels close to 100%) for these devices; thus, their reliability behaviour in such circumstances should be better understood. Thermally activated processes were studied in several previous publications, but less information is available regarding high-humidity environmental tests. Moisture and temperature ageing tests with appropriate environmental parameter settings were performed as accelerated lifetime tests to investigate not only the effect of temperature but also that of humidity on the ageing and reliability of LED packages containing RGB (red green blue) chips and phosphor-converted white (pcW) LEDs. The ageing was followed not only through monitoring optical/electrical/spectral parameters but also with material analysis. Moisture-material interaction models were proposed and set up. It was found that humidity-accelerated ageing processes are more severe than expected from previous assumptions. RGB and pcW LEDs showed strongly different behaviour.

A Robust Anti-Thermal-Quenching Phosphor Based on Zero-Dimensional Metal Halide Rb3InCl6:xSb3.

High-power phosphor-converted white light-emitting diodes (hp-WLEDs) have been widely involved in modern society as outdoor lighting sources. In these devices, due to the Joule effect, the high applied currents cause high operation temperatures (>500 K). Under these conditions, most phosphors lose their emission, an effect known as thermal quenching (TQ). Here, we introduce a zero-dimensional (0D) metal halide, Rb3InCl6:xSb3+, as a suitable anti-TQ phosphor offering robust anti-TQ behavior up to 500 K. We ascribe this behavior of the metal halide to two factors: (1) a compensation process via thermally activated energy transfer from structural defects to emissive centers and (2) an intrinsic structural rigidity of the isolated octahedra in the 0D structure. The anti-TQ phosphor-based WLEDs can stably work at a current of 2000 mA. The low synthesis cost and nontoxic composition reported here can herald a new generation of anti-TQ phosphors for hp-WLED.

Partial substitution-induced luminescent improvement in Dy3+-activated tellurooxyphosphate phosphor

A series of Dy3+-doped tellurooxyphosphate-based phosphors: Na3Ca4-x(TeO3)(PO4)3:xDy3+ and Na3Ca3.91-yGdy(TeO3)(PO4)3:0.09Dy3+ were obtained by a microwave-assisted synthesis, aiming to develop photoluminescent materials suitable for phosphor-converted white light-emitting diodes (pc-wLED). The effect of Gd3+ partial substitution on the luminescent enhancement of Na3Ca3.91-yGdy(TeO3)(PO4)3:0.09Dy3+ phosphor was investigated in detail. When the substitution amount of Gd3+ is 0.06, the luminescence intensity is significantly enhanced. Simultaneously, the partial substitution of Gd3+ induces the increase of the structural rigidity, leading to higher thermostability and better resistance to chromaticity shifting. The study provides a potential yellow-emitting material for pc-wLED.

Structure tailoring and defect engineering of a highly thermally stable red emitting phosphor

Gd3−yCay−0.02GaO6:0.02Eu2+ (y = 0.2) can produce 650 nm red light with a half-peak width of 68 nm, and its emission intensity can still maintain more than 95% of that at room temperature.

Site occupation, emission color tuning and white LED application of Ce3+-activated chloroborate Ca2BO3Cl

Investigation on Ce3+ ions occupying different cation sites of a specific compound is of great significance for exploring multicolor phosphors. Herein, we report the luminescent properties of Ce3+ in chloroborate Ca2BO3Cl host. Two kinds of Ce3+f-d transitions have been observed via adjusting the doping concentration. The assignment for different Ce3+ sites to certain cation sites is corroborated by structural analysis (XRD), fluorescence spectroscopy (PL) and decay kinetic analysis. Information on the two Ce3+ sites’ wavelengths of the five 5d bands in the Ca2BO3Cl host lattice together with εcfs, ɛc, D and ΔS are obtained. Moreover, with the increasing of Ce3+ doping concentration, the emission peak shows an obviously redshift, and the emission color changes from dark blue to blue. The tuning luminescence properties are attributed to the energy transfer from Ce II to Ce I. The optical properties of the as-fabricated white light-emitting diode (LED) are studied. However, the optical properties of current studied Ce3+ doped Ca2BO3Cl is not good enough to be a candidate for near-UV chip excited phosphor-converted white LED.

Ultra-broadband emission up to 181 nm of VO4-activated yellow phosphor for white light-emitting diodes with high color rendering index

Exploring broadband yellow phosphors capable of covering the cyan to red region is an effective approach to achieve high-performance phosphor-converted white light-emitting diodes (pc-WLEDs). Herein, we synthesized a series of VO4-activated ultra-broadband KSrP1−xVxO4 (0.1 ≤ x ≤ 1) yellow phosphors via high temperature solid-state reaction. Successive substitution of P5+ with V5+ causes a slight expansion of the lattice constant and induces several highly localized energy-levels within the forbidden band. Density functional theory calculations confirm that these newly appeared sharp-line energy-levels are attributed to the constructed VO4 anionic groups. With the optimized V5+ content, the KSrP0.7V0.3O4 phosphor exhibits an ultra-broadband yellow emission centered at 537 nm under 355 nm excitation. Impressively, its full width at half maximum is up to 181 nm, exceeding that of most reported counterparts. At 105 °C, the KSrP0.7V0.3O4 sample experiences an emission loss of 53%. A WLED device is fabricated by using phosphor blend of KSrP0.7V0.3O4 yellow phosphor and the commercial BaMgAl10O17: Eu2+ blue phosphor and a 355 nm NUV LED chip, demonstrating bright white emission with high color rendering index (CRI) of 90 and suitable correlated color temperature of 5953 K. These findings indicate that this phosphor has great potential for achieving high CRI WLEDs.

A negative-thermal-quenching LaMgAl11O19: Er3+, Sm3+ phosphor achieved by energy transfer from Er3+ to Sm3+

Phosphor-converted white light-emitting diodes (pc-wLEDs) are drawing ever-increasing attention towards electronic applications. However, thermal quenching, the intensity decay with increasing temperature, presents a significant challenge for high power operation. We reverse the effect with a negative-thermal-quenching property based on energy transfer from one luminescent center to another center. The LaMgAl11O19: Er3+, Sm3+ (LMA: LaMgAl11O19: Er3+, Sm3+) phosphor has been designed, which shows a positive relationship between emission intensity and operating temperature up to 573 K (300 °C). As the temperature rises, energy transfer from Er3+ to Sm3+ occurs with higher efficiency because of stronger ionic vibration. As a result, the phosphor luminescence intensity at elevated temperatures is enhanced. Our design for negative-thermal quenching phosphor laid the foundation for the research of high-power pc-wLEDs or lasers at higher temperatures. It also has potential for wide-temperature-sensing-range radiometric optical thermometry applications.

A high-efficiency double perovskite phosphor SrLaNaTeO6:Mn4+: Potential applications in w-LEDs and indoor plant growth lighting

A novel deep-red phosphor with Mn4+-doped double perovskites SrLaNaTeO6 (SLNTO) was synthesized by the conventional high-temperature solid-state method. SLNTO contains both [NaO6] and [TeO6] octahedra. The octahedral structure of double perovskites facilitates the doping of Mn4+. The band gap (Eg) of the direct semiconductor SLNTO is 2.88 eV. With an excitation wavelength of 322 nm, SLNTO:Mn4+ has a 700 nm deep-red wavelength emission assigned to the energy level transition from 2E1g to 4A2g of Mn4+ ions. Photoluminescence (PL) of the sample and phytochrome far-red light (PFR) absorption are satisfactory matches. According to the Tanabe-Sugano diagram, Mn4+ is located in the strong crystalline field for 2E1g. A 2.0 mol% concentration of Mn4+ is optimal; further high doping results in concentration quenching, ascribed to the neighbour ion interaction and dipole‒dipole (d-d) interactions. The internal quantum efficiency (IQE) is 87.84 %. Additionally, the electroluminescent (EL) spectrum of the encapsulated plant growth lamp overlaps with the chlorophyll a and b absorption spectra. Its Commission Internationale de l'Eclairage (CIE) coordinates of SLNTO:2.0 mol%Mn4+ phosphor with a near-ultraviolet (n-UV) chip are located in (0.720, 0.280). The phosphor-converted white light-emitting diode (pc-WLED) has a high colour rendering index (Ra = 96) with a suitable correlated colour temperature (CCT = 6240 K). The results are satisfactory for white light-emitting diodes (w-LEDs) and plant growth lamps.

K2CaPO4F:Eu2+,RE3+ for pc-WLEDs: Cationic substitution inducing tunable emission and anti-thermal quenching

Near-ultraviolet (n-UV) chip based phosphor-converted white light-emitting diode (pc-WLED) is proposed as one of the methods to realize full-spectral illumination with high color rendering index (CRI). Accordingly, it is crucial to explore n-UV excitable, efficient, and thermally stable phosphors. Here in, the redistribution of Eu2+ on different crystallographic sites (K and Ca) of K2CaPO4F was achieved by introducing Ce3+ and other optically inert rare earth (RE) ions (La3+, Y3+, and Lu3+). This cationic substitution resulted in the enhancement of blue emission, the weakening of red emission, and the appearance of white emission finally. The introduction of RE3+ not only improves the excitation at ∼400 nm, but also changes the quantum efficiency and thermal stability of the phosphors. For example, the introduction of Y3+ increases the external quantum efficiency from 52 % to 62 %. The introduction of Ce3+, Y3+, and Lu3+ brings traps and therefore results in anti-thermal quenching behavior within 398 K. The pc-WLEDs fabricated by covering a 365/380 nm chip with phosphor blend containing K2CaPO4F:Eu2+,RE3+ can emit a warm white light with a CRI as high as 98. This work provides an effective approach to tune the luminescence properties for high performance solid-state lighting.

Enhancement of luminescence and thermal stability of NaLi3SiO4: Eu phosphor by co-doping K+ ions

High-efficiency phosphor with excellent luminescence properties and thermal stabilities is essential for phosphor-converted white light-emitting diodes (w-LEDs). Compared with red and green phosphors, near-ultraviolet excited blue phosphors with high efficiency and excellent thermal stability are still scarce, and the development of efficient blue phosphors remains challenging. NaLi3SiO4: Eu2+ (NLSO: Eu2+) is a promising narrow-band blue phosphor. In this paper, a series of Na1-yKyLi3SiO4: 5%Eu2+ (0.05 ≤ y ≤ 0.2) phosphors were successfully synthesized by high-temperature solid-state reaction through co-doping a small amount of K+ ions in the matrix, significantly improving their luminescence property and thermal stability. Because of the weaker electronegativity of K+ ions, the emission peaks of Na1-yKyLi3SiO4: 5%Eu2+ were slightly blue-shifted from 467 to 463 nm compared with those of NLSO: Eu2+. With an increase in the number of K+ ions, the luminescence intensity of the phosphors increased. When the content of the K+ ion reached 0.2, the luminescence intensity of the Na0.8K0.2Li3SiO4: 5%Eu2+ (NKLSO: 5%Eu2+) phosphor reached its maximum. Compared to the NLSO: 5%Eu2+ phosphor, the luminescence intensity increased by approximately 300 %. At 150 °C, the luminescence intensity of NLSO: 5%Eu2+ phosphor was retained at 75.98 % compared with room temperature, while the NKLSO: 5%Eu2+ phosphor maintained a luminescence intensity of 84.36 % relative to room temperature, demonstrating excellent thermal stability. The enhanced luminescence performance of the NKLSO: Eu2+ phosphor makes it a promising high-efficiency blue phosphor for phosphor-converted w-LEDs.

High colour rendering index and warm emission of conventional white-LED capped with metal-phthalocyanine/CdSe nanocomposites

Improving the colour rendering indices and chromatic stability of conventional phosphor-converted white light-emitting diodes (WLEDs) is crucial to use them as exclusive replacements for traditional light sources. In this work, we attempt to improve these parameters by depositing a free-standing nanocomposite film of metal phthalocyanine (FePc/NiPc) and CdSe QDs onto the conventional WLEDs.Interestingly, capping WLEDs with organic/inorganic FePc/CdSe or NiPc/CdSe nanocomposites significantly improves their colour rendering index (CRI); R9 has increased from 9 to > 50, while Ra has increased from 70 to > 85. They also slightly shift the colour coordinates of WLEDs to the yellow-red range and convert WLED emissions from cool white to warm white. We also demonstrate the excellent colour stability of all WLEDs covered with MPc/QDs when the operating current and operating time are increased. These organic/inorganic FePc/CdSe or NiPc/CdSe nanocomposites are promising materials for improving the performance of conventional WLEDs.

Mechanoluminescence and photoluminescence properties of Eu3+ -activated SrGa2 O4 phosphors.

Red-emitting Eu3+ activated SrGa2 O4 phosphors were synthesized using a conventional solid-state reaction method. The structural, optical, and luminescence properties were systematically investigated. The synthesized phosphors are single phase with a monoclinic structure. There are no significant changes in the phase and the crystal structure of the host matrix after incorporating Eu3+ ions. The undoped and Eu3+ doped SrGa2 O4 phosphors exhibited good mechanoluminescence (ML) emission without any irradiation with ultraviolet (UV) or gamma rays. Eu3+ -activated SrGa2 O4 phosphors have prominent red emission attributed to 5 D0 → 7 F2 forced electric dipole transition excited at 395 nm. The colour coordinates and purity of the SrGa2 O4 : 0.08 Eu3+ phosphor were calculated to be (0.6102, 0.3810) and 97.6%, respectively. The quantum efficiency is 12.68%, and was better than that of commercially available red phosphors. The ML and photoluminescence studies revealed that the synthesized phosphors can act as potential candidates for stress sensors, UV or near-UV light-emitting diodes (NUV LEDs) and components of phosphor-converted white light-emitting diode (pc-WLED) applications.

Exploring luminescent color tunability and efficient energy transfer mechanism of a single-phased hexagonal nanophosphor for white light emitting diodes (WLEDs) application

Nowadays, NUV-triggered phosphor-converted white light-emitting diodes (pc-WLEDs) have gained prominence as substantial alternatives to conventional incandescent and fluorescent lamps as a source of illumination. In this study, we have successfully developed a Tm3+ codoped La2O3:Sm3+ nanophosphor and investigated its potential suitability for application in white light-emitting diodes (WLEDs). X-ray diffraction (XRD) analysis was conducted to examine the phase impurity and structural characteristics of the synthesized nanophosphor. The analysis confirmed the formation of a single-phase La2O3 nanophosphor with a hexagonal crystal structure. The FT-IR spectrum of the synthesized nanophosphor exhibited distinct peaks associated with the vibrational frequencies of La-O bonds. The peaks observed in the fingerprint region of the spectrum, indicate the presence of La-O atoms in the nanophosphor. However, the HR-TEM analysis confirmed that the prepared nanophosphor had a polycrystalline nature and the observed particle sizes lay within the nanoscale range. The incorporation of Tm3+ ions into the host matrix led to a reduction in the optical band gap, leading to enhanced emission intensity. The photoluminescence (PL) study reveals that the Tm3+ ion exhibited blue emission upon excitation at 360 nm, whereas the Sm3+ ion emits reddish-orange light when excited at 379 nm and 408 nm, respectively. However, under 325 nm excitation, the nanophosphor exhibited a white emission color that resulted from the blending of colors emitted by both Tm3+ and Sm3+ ions. This unique finding suggests that this nanophosphor has the potential to generate white light specifically under this particular excitation wavelength. The efficient energy transfer between Tm3+ and Sm3+ ions was attributed to the electric multipolar interaction between the nearest neighbor ions, leading to a quenching phenomenon. Furthermore, the photometric analysis revealed that the correlated color temperatures (CCTs) associated with the emitted white light were found to be higher than 4000 K. Thus, based on these characteristics, it can be inferred that the prepared nanophosphor has the potential to be utilized as a cool white-emitting nanophosphor for single-phased WLEDs application.

Improved spectral mismatch and performance of a phosphor-converted light-emitting diode solar simulator

<span lang="EN-US">A phosphor-converted light-emitting diode (LED) solar simulator is an illuminance device that produced irradiance intensity and spectral close to the sunlight. It is determined as spectral mismatch, non-uniformity of irradiance, and temporal instability. This paper has improved the LED solar simulator (LSS) system to have a spectral distribution consistent with the AM1.5G spectrum at 100%. It was developed as a new prototype to have the AAA class spectral characteristics, time instability, and inconsistency according to IEC 60904-9. The results showed that an optimal approach was to use phosphor-converted natural white LED (pc-nWLED), combining a monochromatic near-infrared (NIR) (730, 800, 850, 940, and 1,000 nm) as well as the proposed LSS system capable of generating 1,000 W/m<sup>2</sup> irradiation over the test plane of 125×125 mm and operated continuously in a constant temperature LED state for at least 2 hours, therefore suitable for demonstration of solar cell features under standard test condition (STC) in the laboratory.</span>

Highly crystalline Y3Al5O12:Ce3+ phosphor-in-silica glass ceramics for high-power solid-state lighting

The pursuit of high-brightness solid-state lighting (SSL) stimulates the development of all-inorganic color converters with high robustness. It is required that the fluorescent material is able to cope with the extreme condition generated from the irradiation of high-power-density excitation light. As such, in this work, we developed a new composite color converter, i.e., Y3Al5O12:Ce3+ phosphor-in-silica glass ceramic (YAG:Ce3+ PiSGC). Remarkably, the amorphous SiO2 matrix spontaneously transforms into tetragonal SiO2 crystallites during co-sintering with crystallization fraction reaching up to >90% (almost full ceramization). The activation energy for crystallization Ec and Avrami index n of amorphous silica oxide are 298.5 kJ/mol and 1.71, indicating the diffusion-controlled glass crystallization mechanism. The fabricated prototype high-power phosphor-converted white light-emitting diode (pc-wLED) and phosphor-converted white laser diode (pc-wLD) based on YAG:Ce3+ PiSGC show satisfactory photometric/colorimetric parameters. The developed color converters have combined merits of environmental protection property, cost-effective manufacturing, good luminescent performance, and easy scalability. This study highlights a new kind of opto-functional composite material and its application as an efficient color converter in high-power solid-state lightings.

Photoluminescence of Mn2+ in the Borosulfate Zn[B2(SO4)4]:Mn2+ - A Tool to Detect Weak Coordination Behavior of Ligands.

The impact of the surrounding ligand field is successfully exploited in the case of Eu2+ to tune the emission characteristics of inorganic photoactive materials with potential application in e.g., phosphor-converted white light-emitting diodes (pc-wLEDs). However, the photoluminescence of Mn2+ related to intraconfigurational 3d5-3d5 transitions is also strongly dependent on local ligand field effects and has been underestimated in this regard so far. In this work, we want to revive the idea how to electronically tune the emission color of a transition metal ion in inorganic hosts by unusual electronic effects in the metal-ligand bond. The concept is explicitly demonstrated for the weakly coordinating layer-like borosulfate ligand in the Mn(II)-containing solid solutions Zn1-xMnx[B2(SO4)4] (x = 0, 0.03, 0.04, 0.05, 0.10). Zn[B2(SO4)4]:Mn2+ shows orange narrow-band luminescence at 590 nm, which is an unusually short wavelength for octahedrally coordinated Mn2+ and indicates an uncommonly weak ligand field. On the other hand, the analysis of the interelectronic Racah repulsion parameters reveals ionic Mn-O bonds with values close to the Racah parameters of the free Mn2+ ion. Overall, this strategy demonstrates that electronic control of the metal-ligand bond can be a tool to make Mn2+ a potent alternative emitter to Eu2+ for inorganic phosphors.

Full-spectrum and tunable white light emission of germanate glass-ceramic containing defective Zn2GeO4 and Mn2+ ions

The full-spectrum phosphors are key components for improving the light quality of phosphor-converted white light-emitting diodes (pc-WLEDs). In this work, a novel germanate glass-ceramic (GC) doped with Mn2+ was developed to achieve full-spectrum white light emission deriving from the defective Zn2GeO4 crystalline phase and Mn2+ with multisite occupancy. The defective Zn2GeO4 is crystallized in situ from the well-designed precursor germanate glass by a controllable heat treatment. The energy states of intrinsic defects, including oxygen and zinc vacancies and interstitial zinc and oxygen of Zn2GeO4 in GC, have been studied by first-principles calculations. The luminescence property and the energy transfer mechanism between the defect states and Mn2+ ions in the GC material was proposed. Under the UV excitation, the luminescence property can be tuned by adjusting the distribution of Mn2+ ions in between the glassy and crystalline phases. The correlated color temperature (CCT) and color rendering index (CRI) of the UV-excited full-spectrum white light emission can be tuned over a wide range. This combinatorial strategy of intrinsic defects and multisite ion doping for full-spectrum white light emission in GC, which overcomes the limitation of conventional discontinuous white light emitting materials that emit singly from doping ions, has shown good potential for application in pc-WLEDs.

Luminescent properties of the Sr8−xBaxMgY(PO4)7:Eu2+ solid solution

Photoluminescence generated by substituting rare-earth ions on multiple crystallographically independent cation sites within a crystalline host material is one of the most common approaches for creating a full-spectrum phosphor-converted white light-emitting diode (pc-wLED). In this work, a series of complex orthophosphates with the composition (Sr8−xBax)0.99Eu0.08MgY(PO4)7 (x = 0, 1, 2, 3) were synthesized via high-temperature solid-state synthesis. These materials possess five potential substitution sites achieving broadband (5905 cm−1) yellow photoluminescence through multi-site substitution showing a violet-excited photoluminescent quantum yield of nearly 50%. Developing such an efficient broad emission spectrum is crucial for enhancing the color rendering ability of pc-wLEDs. Varying the Sr2+ to Ba2+ shifts the emission color from green-yellow to yellow under violet excitation (λex = 400 nm) while influencing the full-width-at-half-maximum (fwhm). Temperature-dependent photoluminescence measurements indicate that phosphor has good thermal stability with T50, the temperature at which the emission intensity is half of the low-temperature intensity, at 420 K and stable chromaticity coordinates, further supporting that the (Sr8−xBax)0.99Eu0.08MgY(PO4)7 series are promising candidates for LED white lighting. Constructing a prototype pc-wLEDs device using (Sr7Ba)0.99Eu0.08MgY(PO4)7, the highest quantum yield phosphor, produced a functional daylight bulb with a color rendering index (CRI) of 90.

Thiogallate phosphor for white LEDs with water-resistance and green light-emitting capability

The application of sulfide phosphor in the field of phosphor-converted white light-emitting diodes (pc-WLEDs) and wide-gamut displays has been limited by its poor water resistance. Herein, a water-resistant green emission phosphor, LiGaS2:Eu2+ (LGSE), has been developed using a chalcogenometallate LiGaS2 (LGS) as the luminescent host. First-principles calculation was utilized to identify the electronic structure of LGS and the optimal site for the Eu2+ dopant. Upon stimulation by 450 nm light, the LGSE phosphor exhibits a brilliant green emission with a photoluminescence emission (PL) maximum at 544 nm and a quantum efficiency of 55.3%. The exceptional luminance characteristics of this green-emitting phosphor were revealed by diffuse reflection spectra, steady-state PL spectra, and temperature-dependent PL measurements. The LGSE phosphor retains at least 94% of its initial emission even after 20 days of water immersion. The integration of LGSE with a commercial red-emitting K2SiF6:Mn4+ phosphor on a 450 nm blue LED chip produced a warm white light LED device, in which the color rendering index was Ra = 80.3 and CCT = 5128 K. This development represents a significant advancement in the field of water-resistant sulfide phosphors.