Phosphor-in-glass Research Articles

Thermoluminescence dosimetry properties and kinetic parameters of zinc borate silica glass doped with Cu2O and co-doped with SnO2

The glass phosphor thermoluminescence (TL) properties of zinc borate silica (ZBS:45ZnO-45B2O3–10SiO2) doped with various concentrations of Cu2O and then co-doped with various SnO2 was analyzed. The doped sample with 0.005% Cu2O concentration and co-doped with 0.1 mol% SnO2 have a higher TL response among the other concentrations for a delivered dose 50 Gy of Cobalt-60 gamma radiation. The obtained glow curve from the optimum doped and co-doped samples with 0.005% Cu2O and 0.1 mol% SnO2 concentrations are simple with single glow peak. The annealing procedure and heating rate are determined for both optimum samples. TL response within the dose range of 0.5–100 Gy, minimum detectable dose, reproducibility and fading are investigated. Based on analyses of glow curve, linearity, reproducibility, dose threshold, thermal fading, optical bleaching and activation energy frequency factor, the glass with co-doped 0.1 mol% SnO2 found to be suitable as a thermoluminescence dosimeter.

Tailoring Trap Depth and Emission Wavelength in Y3Al5- xGa xO12:Ce3+,V3+ Phosphor-in-Glass Films for Optical Information Storage.

Deep-trap persistent luminescent materials, due to their exceptional ability of energy storage and controllable photon release under external stimulation, have attracted considerable attention in the field of optical information storage. Currently, the lack of suitable materials is still the bottleneck that restrains their practical applications. Herein, we successfully synthesized a series of deep-trap persistent luminescent materials Y3Al5- xGa xO12:Ce3+,V3+ ( x = 0-3) with a garnet structure and developed novel phosphor-in-glass (PiG) films containing these phosphors. The synthesized PiG films exhibited sufficiently deep traps, narrow trap depth distributions, high trap density, high quantum efficiency, and excellent chemical stability, which solved the problem of chemical stability at high temperatures in the reported phosphor-in-silicone films. Moreover, the trap depth in the phosphors and PiG films could be tailored from 1.2 to 1.6 eV, thanks to the bandgap engineering effect, and the emission color was simultaneously changed from green to yellow due to the variation of crystal field strength. Image information was recorded on the PiG films by using a 450 nm blue-light laser in a laser direct writing mode and the recorded information was retrieved under high-temperature thermal stimulation or photostimulation. The Y3Al5- xGa xO12:Ce3+,V3+ PiG films as presented in this work are very promising in the applications of multidimensional and rewritable optical information storage.

Eu2+-activated blue-emitting glass phosphor derived from Eu3+ exchanged USY zeolites by thermal treatment in reducing atmosphere

In this work, we report a facile method to prepare Eu2+ activated blue-emitting glass phosphor via loading Eu3+ into USY (Na28Si168Al28O384·240H2O, Si/Al ratio=6) zeolites’ cavities followed by thermal treatment in reducing atmosphere. The zeolites powders containing Eu3+ were treated at different temperatures from 800 °C to 1200 °C in flowing 5%H2 + 95%N2 ambient. The photoluminescence properties were investigated on aspects of the emission and excitation spectra, internal quantum efficiency (IQE), thermal stability and the fluorescence lifetime. The XRD patterns showed that the sample calcined at 950 °C was of pure glassy state. Under the broad 200–430 nm excitation, a strong blue emission band peaked at 451 nm with a full width of half maximum (FWHM) value of 74 nm was observed for this sample. Under the 365 nm excitation, the samples treated at different temperatures showed monotone red shift in the emission peak wavelengths with the thermal treatment temperature increasing. Transparent glass sheets were obtained from the glass phosphor powders by spark plasma sintering (SPS) at 1200 °C, 1250 °C and 1300 °C. The optical transmittance and thermal conductivity of transparent glass sheets were measured. The results indicated that this glass phosphor may be a potential candidate material for white LEDs.

Preparation and luminescent performances of thermally stable red-emitting phosphor-in-glass for high-power lighting

Phosphor-in-glass (PiG) has become as a promising resin-free color converter for high-power light-emitting diodes (LEDs). However, the challenge in luminescent performances of PiG still remain due to the deficiency of red emission spectrum. Herein, a stable red-emitting PiG was prepared for high-power lighting by introducing 3.5MgO·0.5MgF2·GeO2:Mn4+ (MFG:Mn4+) phosphor particles into a tellurite glass matrix. The microstructures and luminescent performances of prepared PiGs were investigated. PiG-based LEDs were fabricated by combining the prepared PiGs and ultraviolet (UV)-LED chips and their optical performances were adjusted by altering phosphor content. Consequently, the introduced phosphor crystals are chemically stable under sintering process and maintain intact in the glass matrix. With the increase of phosphor content, the red emission intensity is increased. Furthermore, the prepared PiG weakens the thermal quenching of MFG:Mn4+ phosphor and exhibits excellent thermal stability under high temperature operation. The results demonstrate that the prepared PiG is a stable and efficient red-emitting converter for high-power lighting.

Continuously tunable broadband emission of Mn2+‐doped low‐melting point Sn–F–P–O glasses for warm white light‐emitting diodes

AbstractTin fluorophosphate (TFP) glass, which can be used to manufacture a phosphor‐in‐glass (PiG) for achieving high‐power white light‐emitting diodes (w‐LEDs), has attracted a great deal of attention because of its low‐melting point. Mn2+‐doped ultralow glass transition temperature (~122°C) Sn–F–P–O glasses were prepared to achieve broadband visible light emission from 390 to 720 nm. By controlling the concentration of MnO, the emission color of the TFP glass can be adjusted from blue/cool white to warm white/red. In particular, 0.2 mol% MnO‐doped TFP glass, which yields bright and warm white light and has ultralow glass transition temperature and thermal stability, has a promising application prospect in the field of high‐power w‐LEDs.

Photonic crystal assisted up-converter based on Tb3+ / Yb3+ - Doped aluminosilicate glass

Great efforts have been made in the last few years to increase the energy efficiency of solar cells. Among several factors which influence their performance, the light harvesting efficiency is the most relevant factor. In order to reduce the transparency losses of sub-bandgap solar photons, especially for wide gap solar cell materials, the development of up-conversion (UC) coatings to transform near infrared (NIR) light into short-wavelength visible photons is clearly a suitable approach. In spite of recent advances, the development of UC materials involves techniques which are generally not cost effective. This work will primarily focus on the evaluation of UC luminescence in aluminosilicate glass phosphors co-doped with the Tb3+/Yb3+ ion pair and synthesized by sol-gel (SG), a technique which is especially adequate to the deposition of films. The optimization of dopant concentrations has also been investigated, together with the structural, morphological and UC emission study of the coatings obtained. Lastly, a potential demonstrator has been developed in the form of a 1-D photonic crystal (PC) microcavity, in order to integrate the spectral conversion function into a more complex but more efficient structure.

Preparation and luminescent properties of new YAG:Ce3+ phosphor in glass (PIG) for white LED applications

A yellow-emitting phosphor-in-glass (PIG) material was synthesized by dispersing commercial YAG:Ce3+ phosphor powder in homemade host glass prepared by melting-quenching method. The phase composition, microstructure and photoluminescence properties of PIG were investigated by means of XRD, SEM, fluorescence spectrophotometer and optoelectronic testing system. The results showed that the YAG:Ce3+ phosphor particles were uniformly distributed and well preserved in glass matrix without any decomposition reaction. The bulk PIG can be efficiently exited by 460 nm to emit a broad yellow emission peak (530 nm) attributed to 5d → 4f transition of Ce3+ ion. The optimal luminous property of PIG can be achieved when YAG:Ce3+ phosphor concentration, melting temperature and thickness are 8 wt%, 950 °C and 1.5 mm, respectively. Under driving current of 540 mA, the luminous efficiency of the white LED device packaged by the as-prepared PIG and blue LED chip is 98 lm/W, and its color coordinate, color temperature and color rendering index are (0.300, 0.339), 7125 K and 71, respectively. This finding shows potential applications in white LEDs for the as-prepared PIG material.

Photon Quantization in Sm3+ Doped Red Glass Phosphors for Laser‐Induced Illumination

Multi‐peak red fluorescence emissions in Sm3+‐doped multicomponent‐alkali‐alkaline‐borate (MCAAB) glasses for laser‐induced illumination are quantitatively characterized, revealing that the quantum yield (QY) is closely related with the wavelength of pumping sources. Under the excitation of 370 nm UVA‐LED, the net emission photon numbers of 1.00 wt% Sm2O3‐doped MCAAB glasses are derived to be 58.0 × 1012 cps, and the QY reaches to 25.3% which is about twice as much as 12.2% under 469 nm blue‐LED pumping, which is attributed to the better excitability in UVA spectral region. In order to extend the effective excitation range to UVB, Ce3+ is co‐doped in Sm3+‐doped MCAAB glasses as a sensitizer, which results in an enhancement of Sm3+ excitation intensity by a maximum sensitization factor of 9.16 in the UVB region. Absolute spectral parameters under 453 nm blue laser excitation exhibit that net emission photon numbers are up to 199.4 × 1012 cps in 1.00 wt% Sm2O3 doping case, and QY is solved to be 6.2%. Higher QY of the Sm3+‐doped MCAAB glasses is expected to be achieved by further adopting wavelength‐matched pumping laser, implying that Sm3+‐doped MCAAB glasses is a promising candidate as high power‐density light source in special laser‐induced illumination.

Low-Yellowing Phosphor-in-Glass for High-Power Chip-on-board White LEDs by Optimizing a Low-Melting Sn-P-F-O Glass Matrix

We introduce a low-melting-point (MP) Sn-P-F-O glass ceramic material into the phosphor-in-glass (PIG) material to realize an ‘on-chip’ chip-on-board (COB) type of phosphor-converted (pc) white light-emitting diode (WLED) with green (BaSr)2SiO4:Eu2+ and red (SrCa)AlSiN3:Eu2+ (SCASN) phosphors. The optimum Sn-P-F-O-based ceramic components can be sintered into the glass phase with a facile one-step heating process at 285 °C for 1 min. Specifically, these soft-fabrication conditions can be optimized to minimize the degradation of the luminescent properties of the red SCASN phosphor as well as the green silicate phosphor in PIG-based white COB-type pc-LEDs owing to the low thermal loss of the phosphors at low fabrication temperatures below 300 °C. Moreover, the constituents of the COB package, in this case the wire bonding and plastic exterior, can be preserved simultaneously from thermal damage. That is, the low sintering temperature of the glass ceramic encapsulant is a very important factor to realize excellent optical qualities of white COB LEDs. The optical performances of low-MP Sn-P-F-O-based PIG on-chip COB-type pc-WLEDs exhibit low yellowing phenomena, good luminous efficacy of 70.9–86.0 lm/W, excellent color rendering index of 94–97 with correlated color temperatures from 2700 to 10000 K, and good long-term stability.

Anti-copy and authenticity verification method for ceramic products: Development of new glass phosphor with two optical features

Anti-copy and authenticity verification method for ceramic products: Development of new glass phosphor with two optical features

Lithium-aluminum-zinc phosphate glasses activated with Tb3+ and Tb3+/Eu3+ for green laser medium, reddish-orange and white phosphor applications

A spectroscopic analysis of Tb3+ and Tb3+/Eu3+ doped lithium-aluminum-zinc phosphate glasses is performed through their absorbance and photoluminescence spectra, and decay time profiles. Laser parameter values (stimulated emission cross section, effective bandwidth, gain bandwidth and optical gain) were obtained for the terbium 5D4 → 7F5 green emission from the Tb3+ singly-doped glass (LAZT) excited at 350 nm to judge the suitability of the glass phosphor for fiber lasers. A quantum yield of (47.68 ± 0.49)% was measured for the 5D4 level luminescence. Upon 350 nm excitation the LAZT glass phosphor emits green light with a color purity of 65.6% and chromaticity coordinates (0.285, 0.585) very close to those (0.29, 0.60) of European Broadcasting Union illuminant green. The Tb3+/Eu3+codoped glass emission color can be tuned from reddish-orange of 1865 K upon 318 nm excitation to warm white of 3599 K and neutral white of 4049 K upon 359 and 340 nm excitations, respectively. Upon Tb3+ excitation at 340 nm Eu3+ is sensitized by Tb3+ through a non-radiative energy transfer with an efficiency of 0.23–0.26. An electric dipole-dipole interaction might be the dominant mechanism in the Tb3+ to Eu3+ energy transfer taking place into Tb3+ - Eu3+ clusters.

Tailored white light emission in Eu3+/Dy3+ doped tellurite glass phosphors containing Al3+ ions

Tellurite glass systems modified by addition of aluminum fluoride AlF3 have been successfully synthesized as host matrices for optically active rare earth ions RE3+ (RE3+ = Eu3+, Dy3+). Samples with different Eu3+ to Dy3+ molar ratio have been studied in order to determine possibility of white light emission via UV excitation. Structural investigations confirmed amorphous character of materials whereas spectroscopic studies brought more insight into glass network's nature. FTIR results shown presence of two features related to tellurite glass matrix (in 490–935 cm−1 spectral region) and another one (940-1250 cm−1) due to aluminum addition. Especially, Al-O and Te-O-Al bonds of AlO4 tetrahedrons have been found. AlO4 units are considered as glass formers that improve network's strength and thermal resistivity against devitrification. Based on XPS studies of Al3+ photoelectron band the existence of Al-O and also Al-F bonds have been examined. Moreover, signals originating from Eu3+ and Dy3+ have been found confirming their valence state. Luminescence results revealed possibility of simultaneous UV excitation of Eu3+ and Dy3+ ions. Excitation with λexc = 390 and 393 nm resulted in white light generation starting from warm white to neutral and cool white depending on Eu3+ concentration and used excitation wavelength. Additionally, increase of decay lifetime of Eu3+ induced by Al3+ presence have been revealed based on luminescence decay analysis. Thus, tellurite glass systems modified by AlF3 and doped with Eu3+/Dy3+ may be considered as promising candidates for white light emitting sources.

New down-converter for UV-stable perovskite solar cells: Phosphor-in-glass

Degradation of hybrid lead halide perovskite by UV light is a crucial issue that limits the commercialization of lead halide perovskite solar cells (PSCs). To address this problem, phosphor-in-glass (PiG) is used to convert UV to visible light. Down-conversion of UV light by PiG dramatically increases UV-stability of PSCs and enables PSCs to harvest UV light that is currently wasted. Performance of PSCs with PiG layer does not change significantly during 100 h-long UV-irradiation, while conventional PSCs degrade quickly by 1 h-long UV-irradiation. After 100 h long UV-irradiation, power conversion efficiency of PSCs with PiG is 440% larger than that of conventional PSCs. This result points a direction toward PSCs which are very stable and highly efficient under UV light.

Unique Color Converter Architecture Enabling Phosphor-in-Glass (PiG) Films Suitable for High-Power and High-Luminance Laser-Driven White Lighting.

As a next-generation high-power lighting technology, laser lighting has attracted great attention in high-luminance applications. However, thermally robust and highly efficient color converters suitable for high-quality laser lighting are scarce. Despite its versatility, the phosphor-in-glass (PiG) has been seldom applied in laser lighting because of its low thermal conductivity. In this work, we develop a unique architecture in which a phosphor-in-glass (PiG) film was directly sintered on a high thermally conductive sapphire substrate coated by one-dimensional photonic crystals. The designed color converter with the composite architecture exhibits a high internal quantum efficiency close to that of the original phosphor powders and an excellent packaging efficiency up to 90%. Furthermore, the PiG film can even be survived under the 11.2 W mm-2 blue laser excitation. Combining blue laser diodes with the YAG-PiG-on-sapphire plate, a uniform white light with a high luminance of 845 Mcd m-2(luminous flux: 1839 lm), luminous efficacy of 210 lm W-1, and correlated color temperature of 6504 K was obtained. A high color rendering index of 74 was attained by adding a robust orange or red phosphor layer to the architecture. These outstanding properties meet the standards of vehicle regulations, enabling the PiG films with the composite architecture to be applied in automotive lighting or other high-power and high-luminance laser lighting.

Flexible fabrication of a patterned red phosphor layer on a YAG:Ce3+ phosphor-in-glass for high-power WLEDs

We proposed a flexible and mask-less approach to directly fabricate a patterned red phosphor layer on a Y3Al5O12:Ce3+ (YAG:Ce3+) phosphor-in-glass (PiG) for high-power white light-emitting diodes (WLEDs). This approach was realized by ultraviolet (UV) assisted and initiative cooling based water condensing. A low-temperature precursor glass matrix with a high refractive index was synthesized for the YAG:Ce3+ PiG. By controlling the UV pre-curing time, the micro-concaves with adjustable sizes were fabricated on the red phosphor layer embedded with UV-curable polymer. With the pre-curing time of 20 s, 30 s, and 40 s, the average aspect ratio of the micro-concave is 1.03, 0.76, and 0.41, respectively. Consequently, the patterned sample achieves a highest luminous efficacy (LE) of 108.5 lm/W at the current of 350 mA, which is 16.2% higher than the unpatterned sample. The corresponding correlated color temperature (CCT) and color rendering index (CRI) are 4831 K and 80.5, respectively. The results demonstrate that the YAG:Ce3+ PiG coated with the water condensing patterned red phosphor layer is a feasible and effective method to enhance the light extraction and color quality of high-power WLEDs.

Eu3+‐doped glass as a color rendering index enhancer in phosphor‐in‐glass

AbstractA new method for improving color rendering index (CRI) and low correlated color temperature (CCT) in high‐power white‐light‐emitting diodes (WLEDs) is proposed. We used a configuration of phosphor‐in‐glass (PIG) and studied light output changes with the increment in concentration of yellow‐emitting Y3Al5O12:Ce3+ (YAG:Ce3+) phosphor. The PIG was coupled on the top of blue‐light‐emitting diodes (LED) chip (465 nm). To compensate the lack of red emission in the phosphor, Eu3+‐doped tellurium glass with different europium content was employed as a red emitter. The suitable contents of YAG:Ce3+ and Eu3+ were 7.5 weight percent (wt%) and 3 mol percent (mol%), respectively. The CRI value went from 72 to 82, whereas the CCT was reduced from 24 933 to 6434 K. The proposed structure can improve CCT as well as CRI of WLEDs just by placing a glass on top.

Phosphor-in-glass with Nd-doped glass for a white LED with a wide color gamut.

A phosphor-in-glass (PiG) with red and green phosphors using Nd-doped glass as a host matrix was fabricated to produce a white light emitting diode (wLED) with a wide color gamut. The Lu3Al5O12:Ce3+ and CaAlSiN3:Eu2+ contents were adjusted to achieve white emission for liquid crystal display (LCD) applications. The silicate glass was doped with varying concentrations of Nd2O3 to modify the photoluminescence spectra of the wLED, by the hypersensitive absorption of the Nd3+:I9/24→G5/24,G27/2 transition. The color coordination, the color rendering index, and the color co-related temperature of the PiG-mounted LEDs were modified by the introduction of Nd3+. The color gamut of the wLED was monitored and found to have effectively improved with the Nd3+-doped silicate glass.

Mn-Doped cesium lead halide perovskite nanocrystals with dual-color emission for WLED

CsPbX3 perovskite nanocrystals (NCs) are promising materials for light-emitting optoelectronics, which possess optically tunable bandgap, bright photoluminescence (PL), and excellent photoluminescence quantum yield. However, doping this new class of promising NCs with optically active or magnetic transition metal ions are still limited. Based on the status quo, we synthesized Mn-doped CsPbCl3 and CsPb(Cl/Br)3 NCs by one-pot synthesis method using MnCl2·(H2O)4 as the precursor. The intensity and position of this Mn-related emission are also tunable by altering the experimental parameters, such as reaction temperature and the Pb-to-Mn feed ratio. Highly homogeneous spectral characteristics of Mn luminescence from an ensemble of Mn-doped CsPbX3 NCs, and well-defined electron paramagnetic resonance spectra of Mn2+ in host CsPbX3 NCs lattices suggest relatively uniform doping sites, likely from substitutional doping at Pb2+. In spite of the excellent luminescent properties of Mn-doped CsPbX3 NCs, their instability is still an important issue that obstruct their practical applications. In this paper, we reported a screen printing technology to prepare Mn-doped CsPbCl3 epoxy resin (ER) orange film for enhancing the stability of Mn-doped CsPbCl3 NCs. More importantly is that we fabricated NCs-ER with Y3Al5O12:Ce3+ (YAG:Ce3+) phosphor-in-glass (PiG) realized the chromaticity tuning for YAG:Ce3+ phosphor with white light-emitting-diodes (WLED). In short, warm WLED were constructed by blending the Ce-PiG and orange Mn-doped CsPbCl3-ER materials with the InGaN blue chips.

Highly stable and tunable white luminescence from Ag-Eu3+ co-doped fluoroborate glass phosphors combined with violet LED.

Ag-Eu3+ co-doped fluoroborate glass phosphors doped with various Eu3+-concentrations were prepared by a melt-quenching technique. The luminescent properties of these glass phosphors were characterized by excitation and emission spectra. Broad excitation and emission bands located, respectively, at 300-450 nm and 390-700 nm originating from silver aggregates were observed. Strong red emissions were detected under 404 nm violet light-emitting diode (LED) excitation for those Ag-Eu3+ co-doped samples. It was found that these red emissions of Eu3+ well compensated the deficiency of the red spectral components in glasses containing Ag aggregates. In addition, it was confirmed that stable white light could be achieved from the combination of a specific Ag-Eu3+ co-doped fluoroborate glass phosphor and LEDs with different output wavelengths. By adjusting the luminescence intensity ratio of the glass phosphor to the 404 nm violet LED, tunable emitting color was realized, and the studied glass phosphors showed excellent emitting color stability toward LED drive currents. Our results demonstrated that this kind of easy fabrication, low-cost, and highly stable Ag-Eu3+ co-doped fluoroborate glass phosphors had potential application in white LED.

Chromaticity-tunable color converter of CaAlSiN3:Eu2+ red phosphor film layer stacked YAG PiG for warm-WLED

We realized a facile chromaticity tuning for the YAG:Ce3+ phosphor-in-glass (PiG) based WLEDs (white light-emitting diodes) by tape casting CaAlSiN3:Eu2+ red film layer on PiG plate and then encapsulated to a remote-type stacking configuration. Experimental results indicated that the color converting material realized a tunable chromaticity quality and yield high luminous efficiency. Microstructures were investigated to reveal the state of phosphor dispersion, as well as interaction of PiG substrate with red film layer. Besides, the thickness of red films was discussed in detail to illustrate its influence on the luminous properties. The optimized WLED exhibits excellent optical performance with a luminous efficiency of 95.76 lm/W, a correlated color temperature of 3949 K, a color rendering index of 82.2, and a color shift deviation from Planckian locus in Duv of 0.0043. The color converter with good heat-resistance performance is expected to be a promising indoor high-quality general lighting source.