High Internal Quantum Efficiency Research Articles

Full-Visible-Spectrum White LEDs Enabled by a Blue-Light-Excitable Cyan Phosphor.

Efficient blue-light-excitable broadband cyan-emitting phosphors may yield full-visible-spectrum white light-emitting diodes (WLEDs) with ultrahigh color rendering (Ra > 95). However, this requires closing the "cyan gap" in the 480-520 nm region of the visible spectrum, which is challenging. Herein, a well-performed cyan-emitting garnet phosphor Ca2LuAlGa2Si2O12:Ce3+ (CLAGSO:Ce3+) is reported. Under 430 nm excitation, the optimal CLAGSO:5%Ce3+ compound exhibits a broadband cyan emission (peak, 496 nm; bandwidth, 102 nm) with a high internal quantum efficiency of 85.6% and an excellent thermal resistance performance (69.1% at 423 K). Importantly, this as-prepared cyan-emitting phosphor provides sufficient cyan emission and enables filling the well-known so-called "cyan gap" between the blue LED chip and the commercial Y3Al5O12:Ce3+ (YAG:Ce3+) yellow phosphor. Impressively, a WLED device fabricated with the optimal CLAGSO:5%Ce3+ sample shows a low correlated color temperature (4053 K) and an ultrahigh color rendering index (Ra = 96.6), as well as an excellent luminous efficacy (74.09 lm W-1). These results highlight the importance of blue-excited broadband cyan-emitting phosphors in closing the cyan gap and enabling human-centric full-visible-spectrum warm WLED devices for high-quality solid-state lighting.

Reconstructing the Surface of K2SiF6:Mn4+ Phosphors toward Enhanced Moisture Resistance for White LED Applications.

The K2SiF6:Mn4+ (KSFM) phosphor featuring efficient ultranarrow red emissions is an outstanding candidate for white light-emitting diode (WLED) applications. However, poor moisture resistance seriously affects its application performance. In this study, a two-step surface reconstruction strategy is proposed to dramatically enhance the moisture resistance of commercially available KSFM phosphors, involving treatment with H2NbF7 and subsequent hydrothermal treatment. The modified KSFM phosphor exhibits a high internal quantum efficiency (IQE) of 98.9% after the two-step surface treatment. Meanwhile, nearly 100% of the initial emission intensity is retained for the modified KSFM phosphor even after aging in high temperature (85 °C) and high relative humidity (85% RH) environments for 6 days, in sharp contrast to only 18.6% retention for the original KSFM phosphor. The relative emission intensity of the modified KSFM remains at 98.9% even after being immersed in water for 6 h. Additionally, the phosphor-converted LED fabricated with the modified KSFM phosphor demonstrated excellent long-term stability, retaining up to 97.9% of initial luminous efficacy after aging under 85 °C and 85% RH conditions for 500 h. The moisture-resistance mechanism is elucidated on the basis of spectroscopic analysis as well as structural and compositional characterization of the phosphor surface layer, which can be attributed to the formation of a robust Mn4+-rare shell with high crystalline quality following this two-step surface treatment. The findings contribute to the performance improvements of KSFM phosphors for industrial applications.

InP-based strain engineered InAs(Sb)/InAsPSb multiple quantum wells with tunable emission and high internal quantum efficiency enabled by Sb incorporation

A type I InAs(Sb)/InAsPSb strain engineered multiple quantum wells light emitting diodes system has been demonstrated. Tensile InAsPSb quantum barriers with a high degree of band offset (∆EC = 116–123 meV, ∆EV = 193–250 meV) were used to compensate for the high compressive strain of the InAs(Sb) quantum wells. The structure was grown on the n+-InAsxP1−x metamorphic buffer with a high degree of relaxation (98%), low surface roughness (0.69 nm), and low dislocation density. Through careful strain engineering design, the compressive strain of InAs(Sb) reaches 0.57%–1.52% without strain relaxation. The incorporation of Sb into the multiple quantum wells not only reduces the bandgap but also improves the interface quality by acting as an effective surfactant. Structural analysis reveals superior quality in InAsSb/InAsPSb multiple quantum wells compared to InAs/InAsPSb multiple quantum wells, demonstrating significantly reduced interface roughness and suppression of the Stranski–Krastanov growth mode. Room temperature electroluminescence measurements show a tunable emission wavelength ranging from 2.7 to 3.3 μm, accompanied by a narrow full width at half maximum value of 45 meV. Photoluminescence analysis indicates that the internal quantum efficiency of InAsSb/InAsPSb multiple quantum wells is 5.5%, which is 7 times higher than that of InAs/InAsPSb.

Thermal stable NaMgLaTeO6:Dy3+ double perovskite yellow phosphors for w-LEDs and latent fingerprint visualization

The novel Dy3+-doped NaMgLaTeO6 (NaMgLaTeO6:Dy3+) phosphors were produced through a high-temperature solid-state reaction. X-ray diffraction (XRD) analysis and Rietveld refinement manifest that the pure phosphor was committed to the space group (P21/m (11)) and features the double perovskite structure. The band gap (Eg) of the direct semiconductor NaMgLaTeO6 is calculated to be 2.065 eV. Under 388 nm excitation, the 4F9/2→6H13/2 energy level transition contributes to the maximum emission peak at 572 nm. Other properties of the phosphor include optimal concentration (x = 5 mol %), high thermal stability, activation energy (Ea = 0.31 eV), and internal quantum efficiency (IQE = 31.44 %). The relevant color coordinate of the white light emitting diode (w-LED) prepared by the phosphor is (0.298, 0.311). The features of the latent fingerprint (LFP) created by NaMgLaTeO6:Dy3+ can be clearly reflected on different surfaces. In summary, NaMgLaTeO6:Dy3+ phosphor has proven high potential in w-LEDs production and LFP detection.

Co-training machine learning enables interpretable discovery of near-infrared phosphors with high performance

Near-infrared (NIR) phosphors based on Cr3+ doped garnets present great potential in the next generation of NIR light sources. Nevertheless, the huge searching space for the garnet composition makes the rapid discovery of NIR phosphors with high performance remain a great challenge for the scientific community. Herein, a generalizable machine learning (ML) strategy is designed to accelerate the exploration of innovative NIR phosphors via establishing the relationship between key parameters and emission peak wavelength (EPW). We propose a semi-supervised co-training model based on kernel ridge regression (KRR) and support vector regression (SVR), which successfully establishes an expanded dataset with unlabeled dataset (previously unidentified garnets), addressing the overfitting issue resulted from a small dataset and greatly improving the model generalization capability. The model is then interpreted to extract valuable insights into the contribution originated from different features. And a new type NIR luminescent material of Lu3Y2Ga3O12: Cr3+ (EPW~750 nm) is efficiently screened, which demonstrates a high internal (external) quantum efficiency of 97.1% (38.8%) and good thermal stability, particularly exhibiting promising application in the NIR phosphor-converted LEDs (pc-LED). These results suggest the strategy proposed in this work could provide new viewpoint and direction for developing NIR luminescence materials.

Enhanced forward emission by backside mirror design in micron-sized LEDs.

Tiny InGaN micro-LEDs (μ-LEDs) play a pivotal role in emerging display technologies, particularly augmented reality (AR) applications. Achieving both high internal quantum efficiency (IQE) and efficient light extraction efficiency (LEE) is essential. While wet chemical etching can recover the IQE after dry etching, it alters the pixel shape, impacting optical properties and reducing the LEE. In this study, we overcome this issue by fabricating 1 μm thin-film-based μ-LED emitter arrays with a metallic backside mirror deposited on a patterned dielectric material around the μ-LED mesa. This concave mirror can be straightforwardly integrated into a thin-film LED process chain, and it redirects photons within the μ-LED structure, enhancing the LEE in the forward direction. Electro-optical measurements show a 2.1-fold improvement in light output within the ±15∘ emission cone compared to μ-LEDs with vertical sidewalls. These findings hold significant implications for μ-LED projection displays, where maximizing the overall efficiency and directionality is critical.

How to Make Semi‐Polar InGaN Light Emitting Diodes with High Internal Quantum Efficiency: The Importance of the Internal Field

How to Make Semi‐Polar InGaN Light Emitting Diodes with High Internal Quantum Efficiency: The Importance of the Internal Field

Optically optimization of thin film light-emitting diodes based on transfer matrix

The evolution of white LEDs, both organic and inorganic, has marked a transformative era in lighting technology known as solid-state lighting. This revolution is driven by electroluminescence, where electron-hole pairs recombine to emit light. While OLEDs have achieved high internal quantum efficiency, limited out-coupling efficiency remains a challenge. Improving light out-coupling efficiency is crucial for enhancing LED performance. This paper employs the Transfer Matrix Method to analyze the optical properties of OLEDs and aims to enhance light coupling, efficiency, and overall impact of LED and OLED technologies.

Impacts and effectiveness of sidewall treatment on the spatially resolved optical properties and efficiency enhancement for GaN-based blue and green micro-LEDs

InGaN-based micro-light-emitting diodes (micro-LEDs) are crucial for efficient full-color micro-displays, but suffer from severe degradation of external quantum efficiency (EQE) with size reduction. In this study, the impacts of chemical treatment on the sidewall condition and the EQE of the 10 μm InGaN-based blue and green micro-LEDs were demonstrated. The sidewall treatment can effectively alleviate the residual damage caused by dry etching and suppress the nonradiative recombination, facilitating the achievement of high internal quantum efficiency (IQE). Nevertheless, the sidewall light extraction of the micro-LEDs with smoother sidewall morphology after tetramethylammonium hydroxide (TMAH) treatment is lower than those with rough and prismatic sidewall surface. By utilizing microscopic hyperspectral imaging, the difference in chromatic properties between the inner region and the whole micro-LED caused by dry etching can hinder the stability of chromatic properties of InGaN-based blue micro-LEDs, which can be alleviated by sidewall treatment. The optimal duration for TMAH treatment is obtained as 10 min for both blue and green micro-LEDs, which is the consequence of the compromise between sidewall light extraction efficiency (LEE) and IQE, whereas the improvement of IQE by sidewall treatment for green micro-LEDs is less significant compared to that for blue ones, which can be attributed to the higher dislocation density and recombination via localized states of green InGaN micro-LEDs. This work demonstrates the evolution of IQE and LEE for blue and green micro-LEDs with different sidewall treatment strategies to achieving the ultimate EQE.

A Lu3Sc2Ga3O12: Eu3+ red-emitting phosphor with excellent optical properties and thermal stability was obtained by partially replacing Lu3+ with Gd3+ / Y3+

A novel red phosphor Lu3(1-x)Sc2Ga3O12: xEu3+(0 ≤ x ≤ 0.3) was successfully prepared by high temperature solid state method. The Lu2.4Sc2Ga3O12: 0.2Eu3+ phosphor shows strong high internal quantum efficiency and thermal stability with values of 64.79 % and 87.0 %, respectively. Based on Lu2.4Sc2Ga3O12: 0.2Eu3+ phosphor, the partial replacement of Lu3+ ions in the host by Gd3+ / Y3+ ions changes the local crystal field environment of Eu3+ ions, resulting in wonderful changes in the luminous center, and the luminous intensity at 593 nm is increased by 3.66 and 3.54 times, respectively. The decay time of Eu3+ ions is analyzed from the perspective of dynamics, and the reasons for the enhancement of luminescence after partial replacement of Lu3+ ions are discussed in detail from two aspects of phosphor structure and crystal field effect around Eu3+ ions. In addition, with the substitution of Gd3+ / Y3+ ions, the thermal stability of the sample is 90.3 %/89.4 % with excellent low thermal quenching. The thermal quenching mechanism is described by combining Debye temperature and activation energy. The sample also has a high internal quantum efficiency IQE=79.03 % / 78.24 %. Finally, under the excitation of 365 nm chip, the phosphors of Lu2.34Sc2Ga3O12: 0.2Eu3+, 0.02Gd3+ and Lu2.34Sc2Ga3O12: 0.2Eu3+, 0.02Y3+ synthesized R-LED device has extremely high color rendering index, Ra is 78.23/77.15 and color temperature is 1640.38 K/1642.97 K. The experimental results show that the Lu2.34Sc2Ga3O12: 0.2Eu3+, 0.02Gd3+ / Y3+ phosphors prepared has a wide application prospect in w-LED devices.

Boosting the efficiency of InGaN-based green LEDs grown on Si through buffer strain engineering

InGaN-based micro-light-emitting diodes (LEDs) grown on Si have gained tremendous interest for full-color displays. Strain management is a key challenge for the epitaxial growth of InGaN-based long-wavelength LEDs on Si because the accumulated compressive strain can severely limit In incorporation and degrade the quality of InGaN multi-quantum wells (MQWs) when the conventional Al-composition step-graded AlN/AlGaN buffer is used for strain control. In this work, we demonstrate a promising approach to effectively reduce the in-plane residual compressive stress of GaN by using an AlN single-layer buffer. The in-plane lattice parameter of the GaN underlayer was increased from 3.183 to 3.189 Å with the residual compressive stress at room temperature reduced from 0.37 to ∼0 GPa, which significantly improved the In incorporation of InGaN MQWs and extended the photoluminescence wavelength from 510 to 550 nm. A remarkably high internal quantum efficiency of 78% was thus achieved for the as-grown InGaN-based green LEDs on Si. This work paves the way for the growth of high-efficiency InGaN-based long-wavelength micro-LEDs.

Achieving zero-thermal quenching of Al2(WO4)3:Eu,Tb red phosphors with low thermal expansion for LEDs

Minimizing the emission loss with rising temperature is important to fundamental research and technological applications of phosphor-converted white light-emitting diodes (pc-WLEDs). Red phosphor materials are crucial for improving the illumination and backlit display quality of pc-WLEDs. In this work, non-hygroscopic Al2(WO4)3:0.05Eu3+,0.05 Tb3+ (AWO:0.05Eu,0.05 Tb) red phosphors with low positive thermal expansion are successfully developed to simultaneously achieve zero thermal quenching (ZTQ) and a highly efficient red emitting. Under the optimal 397 nm NUV light excitation, AWO:0.05Eu,0.05 Tb exhibited a strong red emission at 618 nm with a high color purity (CP) of 99.71 % and a high internal quantum efficiency (IQE) of 80.24 %. Furthermore, a warm pc-WLED device with suitable color coordinates (0.347, 0.317), high color rendering index (CRI = 90.2) and low color correlated temperature (CCT = 4737 K) was fabricated based on the as-prepared red phosphor AWO:0.05Eu,0.05 Tb. The findings suggest that the proposed phosphor holds significant promise as a red component for high-power warm pc-WLEDs, which may open up new ways for the exploration of high-performance lanthanide-activated red phosphors towards versatile applications.

Thermally stable and highly efficient Ta-doped CsV1-xO3 green-light-emitting phosphors for WLED

Owing to their energy-saving and environmentally friendly characteristics, rare-earth-free ultraviolet-excited green-luminescent materials have garnered significant attention. To improve the luminescence efficiencies of green-luminescent materials, this study synthesized Ta-doped CsV1-xO3 green-light-emitting phosphors through a solid-state-reaction method, adopting an optimal Ta doping concentration of 10%. Theoretical calculations and reflection spectra revealed an intrinsic indirect band gap of 2.86 eV for CsV0.9Ta0.1O3, lower than that of CsVO3 (3.63 eV). Under 365 nm excitation, the as-prepared phosphors exhibited broadband emissions ranging from 400 nm to 700 nm, attributed to the 3T2→1A1 and 3T1→1A1 transitions within VO4 tetrahedra. Notably, adding Ta5+ ions to CsVO3 increased its emission intensity by 1.39 times and induced a redshift in its excitation spectrum from 369 to 375 nm. Furthermore, Ta5+ doping significantly distorted the VO4 tetrahedra and influenced the optical properties of the synthesized phosphors. Specifically, the nearest of Cs–V bond length increased, and weak interactions between V5+ ions and Cs + ions led to a 1.5-fold higher internal quantum efficiency (60.49%) of CsV0.9Ta0.1O3 compared to that of CsVO3. Furthermore, CsV0.9Ta0.1O3 demonstrated high thermal stability, retaining 75.57% of its initial intensity even at 140 °C. Overall, these results indicate the potential applicability of CsV0.9Ta0.1O3 as a green-emitting phosphor for white-light-emitting diode applications.

High-efficiency luminescent Eu3+ heavily doped glass prepared from black talc: A promising material for significant applications in W-LED illumination

As a distinguished luminescent matrix, rare earth (RE)-doped glass has garnered considerable attention across lighting, display, laser, and related domains. Nonetheless, the limited luminescent efficiency of such glass imposes constraints on its extensive utilization. In addressing this challenge, we have developed a novel formulation involving heavily Eu3+-doped black talc glass, boasting exceptional optical characteristics. Structural examination has validated the successful synthesis of the parent glass matrix comprising [SiO4] and [AlO4] units. With the escalating of Eu3+ doping concentrations, the glass manifested an upward trend in both density and refractive index. Under the excitation of 393 nm light, the glass exhibited strong red light emission, demonstrating a high internal quantum efficiency (IQE) of up to 84.67 %, surpassing markedly other Eu3+-doped glass variants. Furthermore, even under elevated temperatures reaching 150 °C, the glass retained 86.2 % of its luminescent intensity at room temperature, indicative of superior thermal resilience vis-à-vis alternative glass systems. As a proof-of-concept, we encapsulated a white light-emitting diode (W-LED) assembly employing a 395 nm LED chip, Eu3+-doped glass, BaMgAl10O17:Eu2+ blue phosphor, and Ba2SiO4:Eu2+ green phosphor. The resultant device exhibited favorable chromaticity coordinates (0.3566, 0.3994), boasting a correlated color temperature (CCT) of 4791K and a high color rendering index (CRI) of 91. In summary, this investigation employs black talc ore to synthesize luminescent glass, thereby not only diversifying the application scope of black talc but also augmenting its additional value, while notably enhancing the luminescent efficiency of the glass through heavy Eu3+ doping. Through empirical validation, the significant potential benefits of Eu3+-doped black talc glass in the realm of W-LED lighting were convincingly demonstrated.

Unlocking Cr3+-Cr3+ Coupling in Spinel: Ultrabroadband Near-Infrared Emission beyond 900 nm with High Efficiency and Thermal Stability.

Broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) hold promising potential as next-generation compact, portable, and intelligent NIR light sources. Nonetheless, the lack of high-performance broadband NIR phosphors with an emission peak beyond 900 nm has severely hindered the development and widespread application of NIR pc-LEDs. This study presents a strategy for precise control of energy-state coupling in spinel solid solutions composed of MgxZn1-xGa2O4 to tune the NIR emissions of Cr3+ activators. By combining crystal field engineering and heavy doping, the Cr3+-Cr3+ ion pair emission from the 4T2 state is unlocked, giving rise to unusual broadband NIR emission spanning 650 and 1400 nm with an emission maximum of 913 nm and a full width at half-maximum (fwhm) of 213 nm. Under an optimal Mg/Zn ratio of 4:1, the sample achieves record-breaking performance, including high internal and external quantum efficiency (IQE = 83.9% and EQE = 35.7%) and excellent thermal stability (I423K/I298K = 75.8%). Encapsulating the as-obtained phosphors into prototype pc-LEDs yields an overwhelming NIR output power of 124.2 mW at a driving current of 840 mA and a photoelectric conversion efficiency (PCE) of 10.5% at 30 mA, rendering high performance in NIR imaging applications.

Cr3+‐doped far‐red phosphors with zero thermal quenching and excellent spectral matching for plant lighting application

AbstractFar‐red‐emitting (700−740 nm) phosphors are essential for the fabrication of plant lighting phosphor‐converted light‐emitting diodes (pc‐LEDs). However, the development of highly efficient, thermally stable, and spectrally matched far‐red phosphors still remains a challenge. Herein, far‐red GdAlO3:Cr3+ (GAO:Cr3+) phosphors were synthesized via solid‐state reaction and investigated for plant lighting pc‐LED applications. A low‐temperature flux‐assisted synthesis strategy was adopted to improve the crystalline quality, suppress the defect formation, and maintain the valence state of Cr3+ in the phosphors, finally leading to significant luminescent enhancement (∼10 times). The GAO:Cr3+ phosphors show the 2E sharp‐line emissions around 730 nm, which is highly matched with the far‐red absorption band of plants. The optimized GAO:0.01Cr3+ phosphor exhibits a high internal quantum efficiency of 98.3% and zero thermal quenching even up to 250°C. The fabricated pc‐LED can generate an overall output power of 78.1 mW at 100 mA drive current, with a high energy conversion efficiency of 25.3%. The findings demonstrate the great potential of GAO:Cr3+ as far‐red‐emitting phosphor materials for plant growth pc‐LED applications.

Well Number Dependence of Internal Quantum Efficiency in AlGaN Quantum Wells on Low‐Dislocation Sputtered AlN Templates

The internal quantum efficiency (IQE) and cathodoluminescence intensity line profile of AlGaN multiple quantum well (MQW) structures on low‐dislocation face‐to‐face annealed sputtered AlN (FFA Sp‐AlN) and on conventional metalorganic vapor‐phase epitaxy‐grown AlN (MOVPE‐AlN) templates are evaluated and the effect of the number of quantum wells (QWs) on the IQE is discussed. The higher IQE in the FFA samples is probably due to the lower threading dislocation (TD) density; however, the IQE also increases with the number of QWs although the TD density remains constant. Effective diffusion length increases with the number of QWs, indicating that the AlGaN MQW layer helps to suppress point defect diffusion, resulting in IQE increase. Furthermore, the segregation of point defects into the TDs and point defect diffusion via the TDs may explain the difference in the IQE improvement rate between the MQWs on the FFA Sp‐AlN and MOVPE‐AlN templates.

Effect of Extended Defects on AlGaN Quantum Dots for Electron-Pumped Ultraviolet Emitters.

We study the origin of bimodal emission in AlGaN/AlN QD superlattices displaying a high internal quantum efficiency (around 50%) in the 230-300 nm spectral range. The secondary emission at longer wavelengths is linked to the presence of cone-like domains with deformed QD layers, which originate at the first AlN buffer/superlattice interface and propagate vertically. The cones originate at a 30°-faceted shallow pit in the AlN, which appears to be associated with a threading dislocation that produces strong shear strain. The cone-like structures present Ga enrichment at the boundaring facets and larger QDs within the conic domain. The bimodality of the luminescence is attributed to the differing dot size and composition within the cones and at the faceted boundaries, which is confirmed by the correlation of microscopy results and Schrödinger-Poisson calculations.

Near‐unity quantum efficiency wavelength‐tunable NIR phosphors (Sr2−yCay)Sc1−xSbO6: xFe3+ with excellent thermal stability

AbstractFe3+ ions as near‐infrared (NIR) activators are emerging as an alternative to Cr3+.1–5 However, it is a challenge to develop Fe3+‐activated NIR phosphors featuring tunable optical properties, high efficiency, and thermal stability. Herein, we present a series of near‐unity internal quantum efficiency (IQE), wavelength‐tunable and thermal stability NIR‐emitting phosphors Sr2−yCaySc1−xSbO6:xFe3+ (S2−yCyS1−xS:xFe3+). Sr2ScSbO6:1%Fe3+ (SSS:1%Fe3+) phosphor shows broadband NIR emission at 904 nm and near‐unity IQE under excitation at 300 nm. Experimental and theoretical calculation results demonstrate that introduced Ca ions could increase the bandgap value and Debye temperature (ΘD) of host from Eg = 3.702 eV, ΘD = 609 K of y = 0 to Eg = 3.801 eV, ΘD = 692 K of y = 2. Significantly, the resultant S2−yCyS1−xS:1%Fe3+ NIR phosphors show wavelength‐tunable emission from 904 to 952 nm and high IQE of 84.6%–97.5% as well as enhanced thermal stability (I423K/I298K = 76.9%) of Ca2ScSbO6:1%Fe3+ (CSS:1%Fe3+) in comparison with that (I423K/I298K = 70.6%) of pristine sample. We fabricated an NIR light‐emitting diodes (LED) device by using CSS:1%Fe3+ NIR phosphors with ultraviolet LED chip and demonstrated its potential applications in anticounterfeiting, information encryption, and night vision.

An ultra-intense zero phonon line of Mn4+with the low 2E level energy in Rb2LiAlF6

Herein, Rb2LiMF6:Mn4+ (M= Al, In) phosphors were prepared by the non-equivalent doping of Mn4+. Mn4+ in Rb2LiAlF6 exhibits an ultra-intense zero phonon line (ZPL) detected at 627 nm, due to the highly-distorted symmetry. In contrast, the ZPL at 625 nm for Rb2LiInF6:Mn4+ is very weak. The 2E energy of Mn4+in Rb2LiAlF6 (15,949 cm−1) is lower than that in all reported fluoride phosphors, which may be ascribed to the stronger polarization effect of Li+. Compared with Rb2LiInF6:Mn4+ (5.07 %), Rb2LiAlF6:Mn4+ (6.33 %) has a high internal quantum efficiency (IQE) values of 69.8 % and excellent thermal stability. The white LED packaged with Rb2LiAlF6:Mn4+ (6.33 %) exhibits perfect performances with a high color render index (CRI = 92.3) and low color temperature (CCT =3875 K) as well as a high luminous efficiency (LE = 97.1 lm/W). Therefore, this work provides a promising red-emitting phosphor for high-quality white LEDs.