White-emitting Phosphor Research Articles

Manipulating energy transfer to achieve zero-thermal quenching luminescence in a white-emitting borotellurate phosphor

Energy transfer-induced white-emitting phosphor materials acquired much attention in white light-emitting diode (w-LED) domain. Nevertheless, how to obtain extremely high thermostable luminescence is one of the troubles, which is urgently solved. Diverse strategies were proposed to improve thermal quenching resistance of w-LED phosphors. Herein, a Tm3+−Dy3+ energy transfer (ET) method is manipulated to simultaneously achieve white-emitting and zero-thermal quenching luminescence in Na2Y2TeB2O10 (NYTB), which is constructed via the co-substitution of Tm3+/Dy3+ for Y3+. The ET mechanism and efficiency are determined. The color coordinates (0.3545, 0.3334) of the representative NYTB:0.07Tm3+,0.05Dy3+ phosphor closely resemble (0.33, 0.33) for the standard white light. It is employed to fabricate a w-LED device with low CCT. This work offers an in-depth insight of ET strategy for both obtaining white-emitting and developing extremely high thermostable luminescence.

Novel single phase warm white-emitting phosphor BaLaGaO4:Dy3+,Sm3+ with high thermal stability and color stability

In this study, new phosphors BaLaGaO4 (BLGO) doped with dysprosium (Dy3+) and samarium (Sm3+) ions were created using a high-temperature solid-state method. Characterizations with X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and elemental mapping revealed successful doping and uniform elemental distribution. Then the samples were tested for photoluminescence (PL) spectra, the results indicated that the BaLaGaO4:xDy3+ (BLGO:xDy3+) phosphors emitted strong blue and yellow light upon excitation at 350 nm. The emission peaks were located at 480 and 572 nm, respectively. By introducing different proportions of Sm3+ ions, the BaLaGaO4:0.04Dy3+,ySm3+ (BLGO:0.04Dy3+,ySm3+) samples could be excited at 365 nm, and enhancing the red emission component of the phosphor. Meantime, with increasing Sm3+ content, the correlated color temperature (CCT) decreased from 5507 to 3767 K. And the emission spectrum and decay lifetime of BLGO:0.04Dy3+,ySm3+ confirmed the energy transfer from Dy3+ to Sm3+. Furthermore, at 423 K, the luminous intensity of BLGO:0.04Dy3+,0.04Sm3+ retained 86 % of its strength at 298 K, and the chromaticity shift (ΔS) was only 0.00574, which indicated that the sample had excellent thermal stability and excellent color stability. Finally, using the prepared sample and a 365 nm light-emitting diode (LED) chip, a white light-emitting diode (WLED) was fabricated. The CCT of the manufactured WLED also showed a corresponding reduction (from 3423 to 2814 K). Moreover, under the working conditions of 3.4 V and 0.6A, the thermal imaging obtained after 90 min of WLED operation shows the stability of the packaged WLED at high temperature. These researches show that the phosphor has potential application value in indoor lighting technologies.

Color-tunability and energy transfer of a highly thermal-stable BaZnB4O8:Tb3+/Eu3+ phosphor for single-component w-LEDs

A series of Tb3+ single-doped and Tb3+/Eu3+ co-doped BaZnB4O8 samples with color tuning were efficiently synthesized using the solid-state reaction method. The crystal structure, photoluminescence and the energy transfer process (ET) of the samples were systematically studied. The optimal BaZnB4O8:0.08Tb3+ sample shows efficient green emission, then tunable color was achieved by merely introducing a few of Eu3+ ions owing to the highly efficient ET process from Tb3+ to Eu3+ in the BaZnB4O8:0.08Tb3+/yEu3+ samples. The ET efficiency from Tb3+ to Eu3+ of the BaZnB4O8:0.08Tb3+, yEu3+ samples rose from 32.1 % to 51.6 %, simultaneously the luminescent quantum yield improved from 24.7 % to 36.8 %, as the Eu3+ doping concentration increased from 0.125 % to 2 %. Moreover, the Tb3+/Eu3+ co-doped samples exhibited great thermal stability, keeping about 90.2 % (@150 °C) of their original intensity at room temperature. Finally, white light was achieved by a warm w-LEDs fabricated by coating the BaZnB4O8:0.08Tb3+, 0.0025Eu3+ sample on a 365 nm chip. The w-LEDs showed outstanding performance characteristics, with a CCT of 3869 K and a CRI of 89.3. According to the results, Tb3+/Eu3+ co-doped BaZnB4O8 samples have the potential to serve as single-component multicolor-emitting or white-emitting phosphors upon excitation at near-UV wavelength.

Efficient and tunable white light emitting from Sb3+, Tb3+, and Sm3+ Co-doped Cs2NaInCl6 double perovskite via multiple energy transfer processes

Inorganic lead-free double perovskites have the advantages of low toxicity, broadband emission, and good stability, which make them promising luminescent materials for lighting applications. However, due to the limited regulation of their self-trapped exciton emission, it is still greatly challenging to achieve white light emitting from a single double perovskite host. Herein, efficient and tunable white light is realized in Cs2NaInCl6: Sb3+, Tb3+, Sm3+ double perovskite by controlling the ratios of the doped three ions with blue, green, and red emissions, respectively. The steady-state and transient fluorescence spectra of singly- and doubly-doped double perovskites reveal the existence of multiple energy transfer channels in the triply-doped phosphors, including from Sb3+ to Tb3+, Sb3+ to Sm3+, and Tb3+ to Sm3+. Benefiting from these channels, the color coordinates of the triply-doped phosphors can cross the whole white light area of the CIE chromaticity diagram by adjusting the ratios of the three dopants, and the maximum internal quantum yield of the white light phosphors is 66.61 %. The white emission phosphors show the characteristic of being independent of excitation wavelength within 310–360 nm. Furthermore, the emission intensity at 430 K of the white light phosphor Cs2NaInCl6: 0.01Sb3+, 0.65Tb3+, 0.20Sm3+ remains 50 % of that at room temperature. A WLED device fabricated with the phosphor and a 365 nm LED chip exhibits a high color rendering index of 90.9, correlated color temperature of 5469 K, and CIE coordinates of (0.333 and 0.328). The results indicate that the as-prepared double perovskite materials are promising candidates in the solid-state lighting field.

Structural, photoluminescence and energy transfer investigations of novel Dy3+ → Sm3+ co-doped NaCaPO4 phosphors for white-light-emitting diode applications.

In this study, Dy3+-doped and Dy3+/Sm3+ co-doped NaCaPO4 white-emitting polycrystalline phosphor samples were synthesized using a solid-state reaction method. The samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field-emission scanning electron microscopy (FE-SEM), and Photoluminescence (PL) analysis. The phase purity characterization and crystal structural analysis were done using the Rietveld refinement-based FullProf Suite software. The Rietveld refinement result confirms single-phase formation for both Sm3+ and Dy3+/Sm3+ co-doped NaCaPO4 samples with an orthorhombic structure and with a monotonic change in lattice parameters with doping. The PL studies of the Dy3+-doped samples revealed two emission bands. However, at 352 nm, the Dy3+/Sm3+-co-doped samples revealed distinctive emission bands for both ions. The emission peaks at 480 nm (blue) and 573 nm (yellow) are related to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions; however, the emission peaks at 600 nm and 647 nm are attributed to the 4G5/2 → 6H7/2 and 4G5/2 → 6H7/2 transitions of Sm3+ ions. The intensity of the Dy3+ emissions decreased as the Sm3+ levels increased but the emission intensity of the Sm3+ ions increased. The co-doping of Sm3+ ions in Dy3+-doped phosphors results in unique characteristics due to the energy transfer (ET) from Dy3+ → Sm3+ ions. The effectiveness of this ET from Dy3+ → Sm3+ ions is positively correlated with the dopant amounts of the Sm3+ ions. The interaction mechanisms have been identified as dipole-dipole based on Dexter's energy transfer and Readfield's approaches. All decay curves can be adequately fitted via bi-exponential functions, suggesting the movement of energy between Dy3+ → Sm3+ ions. Temperature-dependent PL measurements and CIE color coordinate analysis reveal excellent luminescent properties, making these Dy3+/Sm3+ co-doped phosphors advantageous for white light-emitting diode (WLED) technologies.

Energy transfer for Ce3+ → Tb3+ → Sm3+ induced bright white emission in single-phase CaLa4(SiO4)3O:Ce3+, Tb3+, Sm3+ phosphors and their application in white-light-emitting diodes.

The emergence of phosphor-converted white-light-emitting diodes has crucial significance in the sustainable development of energy; hence, the evolution of phosphors with eminent luminescence and high stability is imperative. In this study, a tri-doped system composed of rare earth ions Ce3+, Tb3+, and Sm3+ incorporated into a CaLa4(SiO4)3O host is reported, and the energy transfer, tunable single-phase white emission, and favorable thermostability of the Ce3+-Tb3+-Sm3+ system were explored. Rietveld refinement results coincided with the original model of the crystal structure, and a band gap energy of 4.612 eV calculated using density functional theory (DFT) demonstrated the system as an appropriate luminescent host with a wide energy gap. Furthermore, ET processes for Ce3+ → Tb3+, Tb3+ → Sm3+, and Ce3+ → Tb3+ → Sm3+ were investigated via steady-state photoluminescence and decay measurements. Besides, the activation energies of CLSO:3%Ce3+, 9%Tb3+, y%Sm3+ (y = 7, 9) were 0.205 eV and 0.223 eV, respectively, showing outstanding thermal quenching resistance. Devices made with LED beads containing CLSO:3%Ce3+, 9%Tb3+, y%Sm3+ (y = 7, 9) phosphors exhibited bright white light with CCT ≈ 3586 and 3307 K and Ra ≈ 81.0 and 78.5, respectively. This study demonstrates that energy transfer for Ce3+-Tb3+-Sm3+ in a tri-doped system offers an interesting design prospect for promoting single-phase white emission phosphors.

Synthesis and warm white emission performance of single-component Ca7Mg2(PO4)6:Dy3+, Eu3+ phosphor for white light-emitting diodes

A single-component Ca7Mg2(PO4)6:Dy3+, Eu3+ white-emitting phosphor was synthesized by a sol-gel approach. The effects of the amounts of Dy3+ ions and Eu3+ ions on the luminescence characteristics and crystal structure of Ca7Mg2(PO4)6:Dy3+, Eu3+ were systematically investigated. The Ca7Mg2(PO4)6:Dy3+, Eu3+ phosphors had a Ca7Mg2(PO4)6 structure with an R3c (161) space group. The Ca7Mg2(PO4)6:Dy3+ phosphor showed emission peaks at both 484 nm (blue) and 576 nm (yellow), which led to the realization of white light. Furthermore, after codoping Eu3+ ions into the structure, a red emission peak (∼617 nm) appeared in the spectrum as a supplementary red component. A warm white light with a low correlated colour temperature (CCT) is obtained from Dy3+/Eu3+-codoped Ca7Mg2(PO4)6. The luminescence intensity at 483 K still reaches more than 73 % of that at 303 K. The packaged LEDs display a bright warm white light with CCT value and colour rendering index (CRI) of 3878 K and 86.7, respectively, which is comfortable for the human eye. With excellent luminescence performances, the white-emitting Ca7Mg2(PO4)6:Dy3+, Eu3+ phosphor had a significant application potential in the w-LED field.

Using energy transfer to obtain warm white-emitting and thermally stable Ca3Y(AlO)3(BO3)4:Dy3+, Eu3+ phosphors

A series of color-tunable warm white-emitting phosphors Ca3Y(AlO)3(BO3)4:Dy3+,Eu3+ were synthesized and characterized for their crystal structure, luminescence properties, thermal stability, fluorescence decay and energy transfer mechanism. The results show that the optimal excitation wavelength and doping concentration of Ca3Y(AlO)3(BO3)4:Dy3+ phosphor are 350 nm and 0.05 mol%, respectively, and its concentration quenching is mainly caused by the interaction between nearest neighbor ions. Under the excitation at 350 nm, the Ca3Y(AlO)3(BO3)4:Dy3+,Eu3+ phosphor showed prominent emission peaks at 471 nm, 576 nm and 622 nm. The photoluminescence spectrum and lifetime decay curves confirmed the presence of Dy3+→Eu3+ energy transfer in Ca3Y(AlO)3(BO3)4. The phosphor of Ca3Y0·85(AlO)3(BO3)4:0.05Dy3+,0.1Eu3+ exhibited remarkable thermal stability and could maintain 87.68% of the emission intensity at 150 °C. By adjusting the doping ratio of Dy3+ and Eu3+ ions, the CIE coordinates and the related color temperature of Ca3Y(AlO)3(BO3)4:Dy3+,Eu3+ phosphors can be adjusted. The w-LED device packaged with Ca3Y0·85(AlO)3(BO3)4:0.05Dy3+,0.1Eu3+ phosphor can emit warm-white light (Tc = 3284 K, Ra = 72.7). These results suggest that Ca3Y(AlO)3(BO3)4:Dy3+,Eu3+ phosphor can provide a potential alternative for the warm w-LED market.

Spectroscopic characterizations and investigation of Judd-Ofelt intensity parameters of Dy3+-doped Ba2La8(SiO4)6O2 near white light emitting phosphor

A series of Dy3+-activated Ba2La8(SiO4)6O2 phosphors were synthesized using the solid-state method with the objective of developing single host white light emitting phosphors for use in solid state lighting applications. The Dy3+ concentration varied between 0.01 and 0.05 mol%. The as-prepared phosphors crystal structure, optical, and photoluminescent properties (PL), along with energy transfer mechanism and luminescence decay, were investigated. The production of a single-phase Ba2La8(SiO4)6O2 with hexagonal symmetry was verified by the findings of the X-ray diffraction analysis. When the Ba2La8(SiO4)6O2: Dy3+ phosphors are exposed to ultraviolet light, they emit the characteristic yellow PL emissions caused by the 4F9/2 → 6H13/2 transition. The Judd-Ofelt (J-O) parameters (Ω2, Ω4, Ω6) were computed using the excitation spectra. The characteristics of the Dy3+ transition indicate that the asymmetric environment around the ligand was suggested by the trend, which was followed by J-O parameters. Due to the dominance of the electric-dipole transition in the luminescence spectrum, the Ba2La8(SiO4)6O2:0.03Dy3+ phosphor displayed yellowish white emission with CIE coordinates of (0.358, 0.398) and a CCT of 4724 K. The synthesized phosphor may be a useful material in the fabrication of white-emitting phosphor for LEDs application.

Optical tuning and energy transfer of single-phase white-emitting Y3TaO7:Bi3+, Eu3+ for ultraviolet converted pc-WLED with high chromatic stability

Reabsorption and color drift at high temperature hinder the high-quality application of the phosphor-converted white light-emitting diodes (pc-WLEDs) devices, thus it is urgent to develop the single-phase white-emitting phosphors with good chromatic stability. In this work, a series of color-tunable Y3TaO7:Bi3+, Eu3+ phosphors are designed by co-doping Bi3+ and Eu3+ based on the crystal structure information and energy transfer principle between Bi3+ and Eu3+, which can be adjusted to achieve single-phase white emission. By increasing the temperature to a high value of 473 K, the emission peak of Bi3+ ions still present at 470 nm in Y3TaO7:Bi3+ phosphors even when the concentration of Bi3+ ions changes, and the characteristic emission peaks of Bi3+ and Eu3+ basically maintain unchanged throughout in Y3TaO7:Bi3+, Eu3+ phosphors. Finally, the single-phased Y3TaO7:0.025Bi3+, 0.06Eu3+ phosphor was employed with ultraviolet chip to produce a warm WLED device with color rendering index of 81.5, correlated color temperature of 4165 K and the Commission International de I′Eclairage chromaticity coordinates of (0.3645, 0.3347). The results indicate that Y3TaO7:Bi3+, Eu3+ phosphors with high chromaticity stability have great application potential in full-spectrum WLEDs.

Structural and Luminescence Properties of (Ba, Ca) Sio4: Dy3+ Phosphors for White Light Applications

In this report monocrystalline white-emitting phosphors Ba1.3Ca0.7SiO4 : 0.03Dy3+ were synthesized by a low temperature solution combustion method. The thermal, structural parameters and optical properties of the obtained phosphors were characterized by TGA, FTIR, XRD, SEM, EDS, TL, and PL. The mass of the Ba1.3Ca0.7SiO4 (host) sample as a function of temperature and the characteristic information about the composition kinetic analysis of thermal decomposition has provided by TGA. The characteristic spectrum of the sample was examined by FTIR. The structural parameters and appropriateness of the phase formation characterized by XRD. Photoluminescence spectra revealed strong transition at 482 nm (4 F9/2 →6 H15/2), 575 nm (4 F9/2 →6 H13/2) and weak transition at 710 nm (4 F9/2 →6 H15/2). The simulated CIE chromaticity coordinate of Ba1.3Ca0.7SiO4 :0.03Dy3+ falls in the white light region. The TL glow curve, the UV ray induced to the phosphor, and effect of dose response recorded for UV time exposure.

White-emitting orthosilicate phosphor α-Sr2SiO4:Ce3+/Eu2+/K+: a bimodal temperature sensor with excellent optical thermometric sensitivity.

Non-contact temperature sensors with low cost, high reliability and high sensitivity have attracted increasing research interest in recent years. In this study, we synthesized a bimodal optical temperature sensor Sr2SiO4:Ce3+/Eu2+/K+ with excellent thermometric sensitivity through a high-temperature solid-state reaction method. In the matrix of α-Sr2SiO4, Ce3+ luminescence exhibits excellent thermal stability (∼129.1%@250 °C), while Eu2+ shows strong thermal quenching (∼21.7%@250 °C), leading to a significant change in the fluorescence intensity ratio (FIR) of Ce3+ (437 nm) and Eu2+ (550 nm) as a function of temperature. This feature enables the phosphor exhibiting outstanding sensitivity in the temperature range of 298-523 K. To be exact, it demonstrates a maximal relative sensitivity of 0.93% K-1 at 348 K. Its absolute sensitivity linearly increases and reaches 3.46% K-1 at 523 K. Besides, it has a large chromaticity shift (ΔE = 228 × 10-3 in 298-523 K) against temperature, making the temperature change visible to the naked eye. We first demonstrate a CIE chromaticity coordinate technique for temperature sensing with high accuracy and good sensitivity by using the function of x or (x2 + y2)0.5 against T. These unique optical thermometric features allow Sr2SiO4:Ce3+/Eu2+/K+ to serve as an accurate and reliable thermometer probe candidate for temperature sensing applications.

Single-component and white-emitting garnet-type phosphors Li3Y3Te2O12: Dy3+, Eu3+ with tunable color and high thermostability: Synthesis, luminescence and energy transfer

The discovery of novel Dy3+- activated and Dy3+/Eu3+ co- activated Li3Y3Te2O12 phosphors with garnet-type was successfully achieved by high temperature solid-state sintering method. The phase purity, effects of the doping concentration of sensitizer and activator on the phase structure, as well as morphology characterization were ascertained using X-ray powder diffraction, the Rietveld refinement method, Fourier transform infrared spectrum and scanning electron microscope. Morphology and detailed photoluminescence behavior were examined via chromaticity coordinate of International Commission on illumination, steady-state and dynamic fluorescence spectra. The absorption spectrum of phosphors mentioned above possess strong response in the range of 350–400 nm, and the white-light emission spectrum consisting of two comparable intensities of blue- and yellow-emitting. The yellow one belongs to the hypersensitive forced dipole transition of 4F9/2–6H13/2, originated from inversion asymmetry of Dy3+ occupied sites in Li3Y3Te2O12 matrix. The concentration quenching mechanism of Dy3+ were identified to be the interactions between dipoles. Dy3+ → Eu3+ energy transfer phenomenon in Li3Y3Te2O12 host were observed and evaluated via PL curves and decay process. The Dexter’s theory and Reisfeld’s approximation are employed to reveal the energy transfer mechanism between sensitizers and activators and energy transfer efficiency in depth. The results indicate that utilizing Dy3+ → Eu3+ energy transfer was conducive to promote white → red tunable color emission. Furthermore, the as-prepared phosphors have been proved to own excellent thermal stability, indicating that it can be used as a promising single-component and white-emitting candidate in the design of ultraviolet-pumped white solid-state lighting.

Synthesis and luminescence enhancement of white-emitting Ca9La(VO4)7:Dy3+ phosphors through Gd3+ and Al3+ codoping for white-light-emitting diodes

The single-component Ca9La(VO4)7:Dy3+, Gd3+ and Ca9La(VO4)7:Dy3+, Al3+ white-emitting phosphors were prepared through a solid-state method, and the Gd3+/Al3+ was introduced in the structure for photoluminescence enhancement. The XRD results verified that the structure of samples was consistent with the Ca9La(VO4)7 standard phase. The as-prepared Ca9La(VO4)7:Dy3+ exhibited a characteristic white emission consisting of a yellow peak (570 nm) and a blue peak (478 nm), which originated from the electron transitions 4F9/2→6H13/2 and 4F9/2→6H15/2 of Dy3+, respectively. Through the introduction of Gd3+/Al3+ into Ca9La(VO4)7:Dy3+, the luminescence intensity could be enhanced by 1.520 and 1.522 times, respectively, which are due to the crystal-field environmental effect. By combining the Ca9La0.79(VO4)7:0.18Dy3+, 0.03Gd3+ and Ca9La0.82(VO4)6.97:0.18Dy3+, 0.03Al3+ with a n-UV LED chip (λex = 365 nm), the warm w-LEDs with suitable CCT and CRI values were realized. In summary, the Gd3+/Al3+ introduced Ca9La(VO4)7:Dy3+ samples can serve as excellent white-emitting phosphors for white-light-emitting diode applications.

Tunable luminescence and improved thermostability via Tm―Dy energy transfer in a tellurooxyphosphate phosphor

Currently, to solve the restrictions of multiple phosphors-converted white light-emitting diodes (w-LED) such as reabsorption and fabricating cost, the single-phase white-emitting phosphor-based w-LED stands a good chance. In this work, we present a type of color-tunable barium tellurooxyphosphate-based phosphor Ba2TeP2O9 (BTP):Tm3+,Dy3+. Under 362 nm excitation, the emitting white color adjustment is realized due to the efficient Tm3+→Dy3+energy transfer. The energy transfer mechanism is ascribed to the dipole-dipole interaction with the 93.3% efficiency. Moreover, the synergistic effect of the Dy3+→Tm3+back-energy transfer and high Debye temperature contributes to the improvement of the luminescent thermostability. For the representative BTP:0.04Tm3+,0.06Dy3+phosphor, the emission at 423 K has only the intensity loss of 9.3%, relative to the initial value, and the chromaticity shifting level is 12.9 × 10–3, verifying that it has comparable luminescence thermostability to the commercial products (such as CaAlSiN3:Eu2+ and BaMgAl10O17:Eu2+). The BTP:0.04Tm3+,0.06Dy3+-based w-LED exhibits the satisfactory parameters of high Ra (88) and low CCT (3227 K). Our work illustrates an effective energy transfer path between Tm3+and Dy3+for developing white-emitting phosphors with high thermostability for lighting application.

Towards single broadband white emission in Rb0.5K1.5CaPO4(F, Cl): Eu2+ via selective site occupancy engineering for solid-state lighting applications

• A single white emission phosphor is obtained by site-selective occupancy engineering. • The substitution of F by Cl effectively controlled the selective occupation of Eu 2+ . • The R 0.5 K 1.5 CPOF 0.8 Cl 0.2 : 0.5%Eu 2+ has a broad FWHM and excellent thermal stability. • The wLED fabricated with 365 nm chip and the phosphor has high CRI and suitable CCT. Phosphors with single broadband white emission are ideal for solid-state lighting applications. However, achieving single broadband white emission in a single activator doped single component phosphor is very challenging. Herein, by introducing a small amount of Cl - ions into the Rb 0.5 K 1.5 Ca 0.995 PO 4 F: 0.5%Eu 2+ phosphor, we effectively controlled the selective occupation of Eu 2+ ions at Ca sites or K/Rb sites and obtained a single broadband white emission phosphor Rb 0.5 K 1.5 Ca 0.995 PO 4 F 0.8 Cl 0.2 : 0.5%Eu 2+ . The luminescence of this phosphor presents a desirable full width at half maximum (274 nm) and excellent thermal stability (81.9%@150 °C of the integrated emission intensity at room temperature). A white light-emitting diode with high color rendering index (Ra = 93.6) and suitable correlated color temperature (4163 K) was successfully fabricated using Rb 0.5 K 1.5 Ca 0.995 PO 4 F 0.8 Cl 0.2 : 0.5%Eu 2+ phosphor and a 365 nm chip, demonstrating the significant application value of as-prepared phosphors in the field of solid-state lighting. This work provides an effective design strategy for the development of single activator doped single component white light emitting phosphors, which will facilitate the development of related phosphors in the future.

A single-phase white-emitting La(BO3,PO4):Dy3+ phosphor with high thermostability

Developing single-phase white-emitting phosphor has increasingly become an effective strategy to solve the emerging challenges of multiple phosphors-converted white light-emitting diodes such as unavoidable reabsorption, high production cost, and low thermostability. In this work, a single-phase white-emitting La(BO3,PO4):Dy3+ phosphor was synthesized. The photoluminescence performance characterizes the two strong visible emissions of Dy3+: blue (470–500 nm, 4F9/2 → 6H15/2) and yellow lights (570–600 nm, 4F9/2 → 6H13/2). The content quenching of Dy3+ presents at x = 0.03 mol, which is controlled by the dipole–dipole interaction. The optimized product La0.97Dy0.03(BO3,PO4) has a high thermostability. It has also the comparable color coordinates with the ideal white light due to the proper yellow-blue intensity ratio. The above studies confirm that the Dy3+-activated La(BO3,PO4) phosphor could be a prospective white-emitting candidate in lighting application.

Color-tunable blue-emitting Na2MgSiO4:Ce3+ phosphors for white light-emitting diodes

Phosphor-converted white light-emitting diodes (pc-wLEDs) based on near-UV LED chip demand efficient blue-emitting phosphors, because the pc-wLED uses either multi phosphors or single-phase white-emitting phosphor both needs blue-emitting component. When using Ce3+ as the activator, the host structure usually has rare earth ions or alkaline earth ion such as Ca2+ for Ce3+ to occupy, due to similar ionic radius and charge. This work is going to report a blue-emitting phosphor Na2MgSiO4:Ce3+, where Ce3+ occupies the Na+ sites. The phosphor exhibits characteristic of tunable emission color upon increasing Ce3+ content or introducing Li+ as charge compensator. The relationship between the crystal structure and the luminescent properties was studied in detail based on structural refinement and in-depth luminescent studies. The phosphor with a proper Ce3+ content showed a high absolute quantum efficiency of 86.0% and acceptable thermal stability. The pc-wLED made of 365 nm UV chip, the as-prepared Na2MgSiO4:Ce3+,Li+, and commercial green and red phosphors showed good performance with color rendering index of 93.3.

Bi4BPO10:Dy3+: a single-phase white-emitting phosphor for light-emitting diodes

We reported a single-phase white-emitting phosphor Bi4BPO10 (BBP):Dy3+ developed via a solid-state reaction route. Dy3+ activator is introduced into the BBP host by replacing Bi3+ ion with optimal content of 7 mol%. Under 390 nm excitation, due to the suitable combination of characteristic yellow and blue-emitting from Dy3+, the phosphor generates white light. The working temperature-dependent photoluminescence data confirms that it owns a satisfactory thermostability. Finally, the representative BBP:0.07Dy3+ phosphor-converted WLED device is pumped by a n-NV chip to display white light with a CCT of 3731 K. The report indicates that the studied phosphor could be potentially employed for solid-state white lighting source.

Synthesis and photometric properties of efficient white-emitting phosphor of M-AMG transition metal complexes for OLED applications.

Progression in lighting sources mainly depended on new, robust energy-efficient diodes due to their advanced photometric properties. All organic light-emitting sources are constant energy-efficient devices and will be the light of the future. We explore the potential of transition metal complexes by focusing on cobalt(II), nickel(II), and copper (II) with aminoguanidine naphthoate as white phosphors in organic light-emitting diodes (OLEDs). The phosphors synthesized at optimized temperature were characterized structurally and thermally by spectral, thermal, and diffraction techniques. The photophysical studies of the target compound in several organic solvents having divergent polarity were also studied, and the results were exhibited. Photometric properties of the complexes were studied using photoluminescence, CIE (Commission internationale de l'éclairage) chromaticity coordinates, correlated color temperature, color purity, Duv, and TLCI (Television Lighting Consistency Index) to verify the applicability of complexes as phosphors. Excellent luminescence property with a high coloring index for (Cu(2NA-AMG-2H2 O)) opens the advanced avenue for light sources and serves as vital constituents for light-emitting diodes.