Red-emitting Phosphor Research Articles

Spectroscopic investigation of novel Eu3+ doped Na2LiAlF6 fluoroaluminate for solid state lighting applications

Red-emitting phosphors are crucial for sustainable white-light-emitting diodes (WLEDs) used in lighting. These materials significantly enhance the lighting and backlit display quality of phosphor-converted white LEDs (pc-WLEDs) by overcoming red deficiency. Luminescent properties of rare earth activated fluoride based inorganic compounds are most investigated due to its excellent spectral characteristics. In this paper we report the novel Na2LiAlF6 luminescent host material activated with Eu3+ rare earth ions synthesized by wet chemical method. The spectral analysis revels the excitation spanning in near UV region while emission spectra depict characteristic peaks transitioned in accordance with 5D0 to 7F1 and 7F2. Effect of concentration quenching, Color purity and temperature studied briefly which demonstrates that the prepared red emitting phosphor is useful in various device applications such as phosphor converted White light emitting diodes for fulfilment of red deficiency, solid state lighting, display technology as an essential red component.

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.

Synthesis and optical properties of highly efficient Na7Mg13La(PO4)12:Eu3+ powders with excellent thermal stability

In the pursuit of efficient red-emitting phosphors, a series of red-emitting Na7Mg13La(PO4)12:Eu3+ phosphors was prepared using a high-temperature solid-state synthesis method. The phase purity was monitored using powder X-ray diffraction (XRD). The morphological features of the synthesized samples were evaluated by taking scanning electron microscopy (SEM) images. The optical properties of the synthesized polycrystalline samples were investigated by recording room-temperature and temperature-dependent (77–500 K interval) excitation and emission spectra, and photoluminescence (PL) decay curves. The calculated TQ1/2 values were above 420 K, regardless of the Eu3+ concentration, indicating the high thermal stability of the phosphors. The optimal Eu3+ concentration was 100 %, which indicated the absence of concentration quenching in the given host. Furthermore, the quantum efficiency of fully Eu3+-substituted compound reached 100 %, which is an excellent feature for practical phosphor applications.

Ion exchange-assisted surface passivation toward highly stable red-emitting fluoride phosphors for light-emitting diodes

A facile and environmentally friendly ion exchange-assisted surface passivation (IASP) strategy is presented for synthesizing red emitting Mn4+-activated fluoride phosphors. A substantial, pristine Mn4+-free shell layer, applied as a coating to Mn4+ doped potassium fluorosilicate K2SiF6:Mn4+ (KSFM) phosphors, enhances both water resistance and luminescence efficiency. The stability test of fluoride in water at ambient temperature and boiling water demonstrates that IASP-treated KSFM phosphors are highly water resistant. Furthermore, both the negative thermal temperature (NTQ) fitting results and the photoluminescence (PL) decay confirm that the IASP process effectively passivates surface defects, leading to enhanced luminescence performance. The maximum internal quantum yield (QYi) of the IASP-KSFM phosphor is 94.24%. A white LED realized a high color rendering index (CRI) of 93.09 and luminous efficiency (LE) of 149.48 lm/W. This work presented a novel technique for the development of stable fluoride phosphors and has the potential to increase the use of KSFM phosphors in plant supplementary lighting systems and white light-emitting diodes.

Comparing the Luminescence and Moisture Resistance of K3AlF6:Mn4+ Phosphor to Commercial Phosphors

Nowadays, red-emitting phosphors based on Mn4+ doped fluorides with a high color purity and a relatively short decay time can improve the optical performance of WLED. However, they are easily oxidized in humid environment and elevated temperatures. This is the reason why both the brightness and luminous efficiency of WLED quikly decreased. To solve this problem, KF was added throughout the K3AlF6:Mn4+ phosphor synthesis process (KKAFM). This work is focused on aging evaluation of the phosphors and comparing its performance with commercial phosphors (YAG:Ce3+, Sr2Si5N8:Eu2+). Thus, EL spectra of blue LED chips coated with the phosphors were investigated over time in an environment of 85 % RH and 85 oC. The results of EL spectra showed the improvement in the the reduction of the emission intensity of KKAFM. Aging tests of WLEDs using KKAFM and Sr2Si5N8:Eu2+ indicated that KKAFM phosphors exhibited a good stability, thus they can be used as a potential replacement for commercial red-emitting phosphors in WLEDs fabrication.

Photoluminescence and energy transfer studies in the Sm3+ and Eu3+ co-doped Sr2ZnSi2O7 red-emitting phosphors

In this study, we utilized a high-temperature solid-state reaction method to synthesize the red-emitting phosphors, namely Sr2ZnSi2O7:Sm3+ and Sr2ZnSi2O7:Sm3+/Eu3+. Characterization through X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX) revealed that the crystal structure of the as synthesized Sr2ZnSi2O7 samples aligned with the standard JCPDS no. 00-039-0235, featuring small irregularly shaped particles having a tetragonal structure with space group P-421m and space group number 113. The band gap values were determined using diffuse reflectance spectral (DRS) data. Photoluminescence (PL) emission spectra indicated efficient excitation of Sr2ZnSi2O7:Sm3+ and Sr2ZnSi2O7:Sm3+/Eu3+ phosphors under near-ultraviolet light (λex = 404 nm). The PL intensity of Eu3+ ions increased with increasing the concentration of Eu3+ ions, leading to a decrease in the PL intensity of Sm3+ ions. The energy transfer mechanism from Sm3+ to Eu3+ ions is mainly driven by dipole-dipole (D-D) interaction, as predicted using Dexter Reisfeld's approximation. As the concentration of Eu3+ ions increased, there was a reduction in the photoluminescence (PL) decay lifetimes. This decline affirmed the presence of the energy transfer (ET) mechanism from Sm3+ to Eu3+ ions, reaching a maximum transfer efficiency of around 23.11 % in the Sr2ZnSi2O7:Smx/Euy (x = 1.5, y = 5 mol%) phosphor. Computed CIE parameters under UV excitation showed a gradual shift towards the deep red region with increase in Eu3+ concentration. For Sr2ZnSi2O7: Smx/Euy (x = 1.5, y = 5 mol%) phosphor, the CIE color coordinates and color purity were (0.60120, 0.39485) and 95.62 %, respectively. These findings highlight the potential of the synthesized phosphors as solid-state emitters for warm white LED applications, featuring a low color-correlated temperature (CCT) value of 1724 K when stimulated with UV chips.

Synthesis and luminescence properties of Eu3+-activated Mg3(PO4)2 phosphors and substitution of phosphate with molybdate, tungstate and sulphate

In the present work, trivalent europium (Eu3+) ion activated Mg3(PO4)2 red phosphors have been synthesized through solid-state reaction method. X-ray diffraction (XRD) confirmed the successful formation of Mg3(PO4)2:Eu3+ phosphors with monoclinic phase with space group P21/c (14). The photoluminescence (PL) spectroscopy was used to record the excitation and emission spectrum of Eu3+ activated Mg3(PO4)2 phosphor. Under the excitation of 395 nm, the resultant samples exhibited the characteristic emissions of Eu3+ ions corresponding to the 5D0 → 7FJ transitions. The optimal doping concentration of Eu3+ ions was determined to be 0.5 mol%. The Commission Internationale de l'Eclairage (CIE) coordinates of Eu3+ activated Mg3(PO4)2 phosphor is calculated, which shows strong red emission. In addition, phosphate group replaced with molybdate, tungstate and sulfate group and found enhancement in emission intensity of prepared phosphors. The obtained results demonstrated that the Eu3+-activated Mg3(PO4)2 phosphors are very appropriate red-emitting phosphors for applications in near-ultraviolet-excited white Light emitting diodes (LEDs).

Regulating the concentration quenching in Eu3+-activated Lu2W3O12 red-emitting phosphors through phase transition for white light-emitting diode and plant growth applications

Red emission is crucial for fabricating high-quality phosphor-converted light emitting-diode (LED) to satisfy its vivid applications. Herein, Lu2(1-x)W3O12:2xEu3+ (Lu2W3O12:2xEu3+) red-emitting phosphors were developed through sol-gel reaction method. Through adding Eu3+, phase transition, from orthorhombic to monoclinic phase, happened in studied samples. Excited at 394 nm, the resulting phosphors emitted intense red emission and their intensities can be manipulated via phase transition. Specifically, the phase transition can delay concentration quenching in resultant phosphors, of which the optimal state was realized at x = 0.7, resulting in enhanced luminescence properties. Besides, the color purity and thermal stability of prepared phosphors can also be improved by means of phase transition. Based on Judd-Ofelt theory, the local symmetric performances of Eu3+ in synthesized phosphors were analyzed via calculating the corresponding Ω2 values. Via using the designed phosphors as red-emitting components, different types of LED devices were packaged, i.e. red-emitting LED and white-LED. For red-emitting LEDs, their emission bands matched well with the absorption bands of plant pigments, allowing their applications in plant growth, which had been confirmed by rice growth experiments. Furthermore, the packaged white-LED can emit warm white light with high color rendering index and low correlated color temperature, which were slightly impacted by working current. Our finding revealed that phase transition was an efficient route to delay the concentration quenching effect and regulate the luminescence characterizations of Eu3+-activated phosphors.

Preparation of Eu ions doped Sr5(PO4)3F transparent glass ceramics and their luminescence properties

The lack of red light components in solid-state lighting technology urgently requires the development of new efficient red-emitting bulk phosphors. Herein, we successfully prepared a kind of red-emitting glass ceramics (GCs) (λex = 392 nm, λem = 613 nm) containing Eu-doped strontium fluorophosphates (Sr5(PO4)3F:Eu) nanocrystals via a melt-quenching method in SrF2–K2CO3–P2O5–H3BO3 glass. The heat treatment temperature was found to significantly affect the grain size of the Sr5(PO4)3F:Eu nanocrystals as well as the transmittance of the prepared GCs. After heat treatment at 600 °C for 2 h, the Sr5(PO4)3F:Eu nanocrystals with grain size of about 18 nm were precipitated inside the GCs (GC600), which exhibited a high transmittance of 58–70 % in the range of 500–800 nm, with a stronger luminescence intensity than that of PG. Under excitation of 392 and 464 nm wavelengths, the CIE 1931 color coordinates of GC600 were around (0.626, 0.373) and (0.638, 0.362), respectively, both falling in red region. The present Sr5(PO4)3F:Eu GCs are promising as red phosphors for UV-pumped white-light LEDs.

Designing dual-functional lighting via Eu3+-activated MF2 (M2+ = Ca2+, Sr2+ and Ba2+) red-emitting nanoparticles

Developing high efficient and stable red-emitting phosphors is very important in the areas of white lighting-emitting diode (white-LED) and plant growth. Herein, series of Eu3+-activated MF2 (M2+ ​= ​Ca2+, Sr2+, Ba2+) red-emitting nanoparticles (NPs) were synthesized at room temperature. Excited at 394 ​nm, these resulting NPs can emit dazzling red emissions and their fluorescence intensities are sensitive to both dopant content and host compound. Moreover, it is found that the studied samples have admirable thermal stability, high quantum efficiencies and color purities, which can be regulated via changing host material. To assess the possible application of final products, three different white-LEDs were packaged by using Eu3+-activated MF2 (M2+ ​= ​Ca2+, Sr2+, Ba2+) red-emitting NPs. Clearly, these manufactured white-LEDs can produce glaring warm white with satisfied electroluminescence behaviors, i.e. low correlated color temperature (<5000 ​K) and high color rendering index (>80). Furthermore, via using the designed NPs, three red-emitting LEDs were also fabricated so as to identify their applications in plant growth. Our findings imply that Eu3+-activated MF2 (M2+ ​= ​Ca2+, Sr2+, Ba2+) NPs are well-suited for dual-functional lighting as red-emitting converters in the realms of white-LED and artificial plant growth LED.

A novel red-emitting NaYS2 upconversion phosphor under 1550 nm excitation

A novel red-emitting NaYS2 upconversion phosphor under 1550 nm excitation

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.

Tetravalent manganese-doped lithium meta-silicate red-emitting phosphors for LED applications: structural and luminescence properties

In this paper, different concentrations of tetravalent manganese-activated lithium meta-silicate red-emitting phosphors, namely Li2SiO3:xMn4+ (x = 0.01, 0.02, 0.03, 0.04 and 0.05 mol), have been prepared by the solid-state reaction method at 950 °C. The structural, thermal, morphological, and optical properties of the sintered phosphors were characterized by powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), raman, UV-Visible and photoluminescence (PL) spectra. Excitation and emission spectra are used to study optical characteristics, which match well with the commercially visible region. The red emission bands for Li2SiO3:0.02Mn4+ peak at approximately 642 nm (λex = 425 nm) and 717 nm (λex = 475 nm), respectively due to the spin-forbidden 2E → 4A2 transition. The doping concentrations of xMn4+ in the Li2SiO3 host were investigated, and the correlations between Mn4+ doping concentration and luminescence intensity were examined. The Commission Internationale de l'Eclairage (CIE) chromatic coordinate graph confirmed the emission color observation in the red region, showed an excellent color purity (CP). In addition, the quantum efficiency (QE) of Li2SiO3:Mn4+ phosphors reached up to 70.51%. The investigation shows that synthesized Li2SiO3:Mn4+ phosphors are beneficial for red Light-Emitting Diodes (LEDs) used in solid-state lighting.

Synthesis and optical properties of blue-light excitable BaBiNaTeO6:Eu3+ red-emitting bismuthate phosphors for white LEDs

Synthesis and optical properties of blue-light excitable BaBiNaTeO6:Eu3+ red-emitting bismuthate phosphors for white LEDs

Designing high thermally stable deep red phosphors based on low thermal expansion coefficients for optical applications.

Mn4+-activated oxide phosphors with low cost and unique luminescent properties have been considered as a promising candidate for various optical applications, while the search for high thermal stable red-emitting phosphors is still a huge challenge. In our work, we find and unveil the relationship between luminescence thermal quenching behavior and thermal expansion coefficients (α/10-6 K-1) based on double-perovskite niobate phosphors Ca2LnNbO6:Mn4+ (Ln3+ = Y3+, Gd3+, La3+, or Lu3+). It can be concluded that the phosphors with low thermal expansion coefficients contribute to high thermal stability. Subsequently, Ca2LuNbO6:Mn4+ accomplishes accurate temperature testing and high-CRI white light-emitting diodes. Thus, a thermal expansion coefficient strategy is a new guide to select the appropriate substrate with high thermal stability for an Mn4+-activated emitter.

A narrow-band blue emitting phosphor by co-doping Bi3+ and alkali metal ions (Li+, Na+ and K+) with dual luminescence center

The technology of solid-state lighting has developed for decades in various industries. Phosphor, as an element part, determines the application domain of lighting products. For instance, blue and red-emitting phosphors are required in the process of plant supplementing light, arrow-band emitting phosphors are applied to backlight displays, etc. In this work, a Bi3+-activated blue phosphor is obtained in a symmetrical and compact crystal structure of Gd3SbO7 (GSO). Then, the co-doping strategy of alkali metal ions (Li+, Na+, and K+) is used to optimize the performance. The result shows that the photoluminescence intensity is increased by 2.1 times and 1.3 times respectively by introducing Li+ and K+ ions. Not only that, it also achieves narrow-band emitting with the full width of half-maximum (FWHM) reaching 42 nm through Na+ doping, and its excitation peak position also shifts from 322 to 375 nm, which can be well excited by near-ultraviolet (NUV) light emitting diode (LED) chips (365 nm). Meanwhile, the electroluminescence spectrum of GSO:0.6 mol%Bi3+,3 wt%Na+ matches up to 93.39% of the blue part of the absorption spectrum of chlorophyll a. In summary, the Bi3+-activated blue phosphor reported in this work can synchronously meet the requirements of plant light replenishment and field emission displays.

Optical properties and Judd-Ofelt analysis of a novel Red-Emitting monoclinic Li3Ba2Gd3(WO4)8: Eu3+ phosphor

Red-emitting Li3Ba2Gd3(WO4)8: x at.% Eu3+ (0.5 ≤ x ≤ 10) phosphors were effectively produced using a conventional solid-state reaction method at high temperature in air atmosphere. The phosphors exhibited monoclinic crystalline structure with the C2/c space group and 2/m point group. The unit cell parameters determined from the Rietveld refinement for 3 at.% doped sample are a = 5.2149(4) Å, b = 12.7447(1) Å, c = 19.2058(3) Å, α = γ = 90°, β = a^c = 91.9315(1)° and Vcalc = 1275.748(2) Å3. Photoluminescence spectra, lifetimes, colour coordinates and purity, and temperature-dependent emission spectra have been systematically studied. Upon excitation at 395 nm, the phosphors displayed red emission with a peak centered at 614 nm, which was associated with the 5D0→7F2 electrical dipolar transition of Eu3+. At the same time, the influence of different Eu3+ ion concentration on the photoluminescence intensity is also discussed. The optimal concentration of Eu3+ ions in Li3Ba2Gd3(WO4)8 was found to be 3 at.%. The mechanism behind concentration quenching was ascribed to dipole–dipole interactions, and the critical distance for energy transfer among Eu3+ ions was determined to be 7.409 Å. The Judd–Ofelt theory was utilized to assess the intensity parameters and radiative properties. The fluorescence decay times were also determined for the different concentration levels of Eu3+ cations. The chromatic coordinates of Li3Ba2Gd3(WO4)8: Eu3+ were found to be (0.653, 0.345), closely resembling the standard red light (0.670, 0.330) and demonstrated high colour purity (98.42 %) under excitation at 395 nm. Moreover, the phosphors Li3Ba2Gd3(WO4)8: Eu3+ exhibited favorable thermal stability, characterized by an activation energy of 0.219 eV. The aforementioned findings indicate that the phosphors Li3Ba2Gd3(WO4)8 doped with Eu3+ have the potential to function as a red-emitting phosphor in near-ultraviolet-driven white light-emitting diodes.

Thermally Stable Red-Emitting Ca18K3Sc(PO4)14:Mn2+ Phosphor and Enhanced Luminescence by Energy Transfer Between Ce3+-Eu2+-Mn2.

It is significant and valuable to investigate novel and high-performance red-emitting phosphors for high-quality wLED applications. Based on this consideration, we developed a novel Mn2+-doped red Ca18K3Sc(PO4)14:Mn2+ (CKSP:Mn2+) phosphor. The emission peak of CKSP:Mn2+ is located at 640 nm, presenting a broadband red emission with a fwhm of 79 nm under 405 nm excitation. The CKSP:1.0Mn2+ phosphor shows superior thermal stability. At 150 °C, the integrated PL intensity and peak intensity of the CKSP:1.0Mn2+ phosphor maintain 93.2 and 85.7% of those at 25 °C, respectively. Through the strategy of energy transfer among Ce3+-Eu2+-Mn2+, the PL intensity of Mn2+ has increased by nearly 118 times, and the quantum yield has improved from 6 up to 72%. The structure-related photoluminescence and energy transfer mechanisms are discussed in detail. The as-fabricated wLED pumped by a 370 nm LED chip combining commercial the green (Sr,Ba)2SiO4:Eu2+ phosphor, blue BaMgAl10O17:Eu2+ phosphor, and the as-synthesized CKSP:1.0Mn2+, 0.02Eu2+, 0.40Ce3+ phosphor shows excellent color quality (CCT = 5555 K, Ra = 87), which indicates that the CKSP:1.0Mn2+, 0.02Eu2+, 0.40Ce3+ phosphor has extraordinary broad prospects in future wLED applications.

Surface passivation of red-emitting fluoride phosphors by aminocarboxyl complexants to achieve high water-resistance for light-emitting diodes

Mn4+-activated fluoride phosphors are promising luminescent materials for use in phosphor-converted white-light-emitting diodes (wLEDs). However, poor water resistance in high humidity environment, one of critical drawbacks of this type of phosphors, has limited their practical applications. To address this issue, we developed a new facile strategy to passivate the surface of phosphors by in situ constructing a dual Mn4+-rare protective layer using well-known aminocarboxyl complexants with mild reducibility and strong complexation property. Ethylenediamine tetraacetic acid (EDTA) was taken as a representative for the research in detail, and a typical Mn4+-doped fluorosilicate phosphor K2SiF6:Mn4+ (KSFM) was selected to demonstrate the reliability of the proposed strategy. The surface passivation was achieved by simply dispersing KSFM in a saturated EDTA aqueous solution (KSFM-sEDTA) or a hydrofluoric acid solution containing a certain amount of EDTA (KSFM-EDTA), and then stirring for a short time at room temperature. The analysis results indicate that the dual Mn4+-rare surface layer is composed of a K2SiF6 matrix shell and an organic coating of residual EDTA and/or its related compounds, and the layer constructed by Method 2 is more significant than that by Method 1. Both the luminescence performance and the water resistance of the passivated KSFM were greatly enhanced while the luminescence characteristics remained unchanged. When the water-eroded KSFM was re-treated with EDTA, the luminescence was dramatically restored due to removal of the manganese hydrolysates and repair of the crystal surface defects. The wLEDs assembled with KSFM-EDTA and KSFM-sEDTA phosphor exhibited intense white light with high luminous efficiency (LE, 170.61 lm/W and 162.51 lm/W), high color rendering index (CRI, 88.3 and 85.9), and low correlated color temperature (CCT, 3680 K and 3805 K), respectively. More importantly, the fabricated wLEDs retained high LE (90.6% and 88.6%) and no remarkable changes of CRI and CCT values after being aged at high temperature and humidity (85 °C, 85%) for 550 h, which are more superior to the wLED assembled with the pristine KSFM.

Eu3+ doped (Y0.75Sc0.25)2O3 red-emitting ceramics with excellent photoluminescence properties for LEDs

Developing narrow-band red-emitting ceramic phosphors with high quantum yield and low thermal quenching is vital for mid to high powder solid state lighting. In this study, a series of (Y0.75Sc0.25)2O3:Eu3+ ceramics were fabricated and their photoluminescence properties were studied. The spectral measurement suggests that the optimal doping concentration of Eu3+ is as high as 14%. The heavily doped samples show strong absorption in the NUV-blue region (particularly 360–420 nm and 460–475 nm), bright red emission dominated by the sharp peak located at 611 nm, CIE chromaticity coordinates close to the NTSC standard value of red emission, and single exponential photoluminescence decay without afterglow. In particular, ((Y0.75Sc0.25)0.86Eu0.14)2O3 ceramic exhibits high QY of 86.9%, high color purity of 96.9%, and low thermal quenching loss of 16% as the temperature increases from 300 to 570 K. The excellent photoluminescence properties highlight the great potential of Eu3+ heavily doped (Y0.75Sc0.25)2O3 red-emitting ceramics as color converters for solid state lighting, which is demonstrated by the outstanding electroluminescence performance of the fabricated red and white LEDs.