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The introduction of K+ into a RbNa3(Li3SiO4)4:Eu2+ phosphor to partially or completely replace Rb+ allows the emission spectrum to be modulated from blue (λ = 473 nm, FWHM = 22.5 nm) to a narrow cyan band (λ = 485 nm, FWHM = 21.1 nm).

Achieving bright photon upconversion under low irradiance is of great significance and finds many stimulating applications from photovoltaics to biophotonics. However, it remains a daunting challenge to significantly intensify upconversion luminescence in small nanoparticles with a simple structure. Herein, we report the amplification of photon upconversion through engineering interfacial density of states between the core and the shell layer in sub-10 nm colloidal rare-earth ions doped fluoride nanocrystals. Through tuning of the metal cations in the shell layer of alkaline-earth-based core/shell nanoparticles, both the interfacial phonon frequency and the density of state are evidently decreased, resulting in the luminescence intensification of up to 8224 times. The generality of this upconversion enhancement strategy has been verified through expansion of this approach to alkali-based core/shell nanoparticles. The engineering of photon density of state in such core/shell nanoparticles enables dynamic display and high-level security information storage.

A series of novel Ba1-xAl2Si3O4N4: xYb2+ yellow-emissive long-afterglow phosphors was successfully synthesized via a high-temperature solid-state reaction with two sintering steps. The phosphors exhibited broad band emission (full width at half maximum, FWHM = 107 nm) with a peak at 518 nm. With an increase in the Yb2+ doping content in Ba1-xAl2Si3O4N4: xYb2+ phosphors, the luminescence intensity reached a maximum at x = 0.15. The long-afterglow phosphor can be activated effectively by 254 nm UV light, and the afterglow can persist for more than 7 h. From the thermoluminescence (TL) spectrum, there are three types of electron traps, with average evaluation depths of 0.485, 0.592, and 0.681 eV. The afterglow is caused by the capture and re-release of free electrons by the three trap energy levels. Finally, the thermal and chemical stability of the phosphor was tested, its luminescence intensity was 78.7% at 150 °C and 99.5% after 5 h soak in water compared to that at room temperature and original, respectively.

Scintillators are of significance for the realization of indirect X-ray detection and X-ray excited optical luminescence (XEOL) imaging. However, commercial bulk scintillators not only require complex fabrication procedures, but also exhibit non-tunable XEOL wavelength and poor device processability. Moreover, thick crystals usually generate light scattering followed by evident signal crosstalk in a photodiode array. Lanthanide doped fluoride nanoscintillators (NSs) prepared with low-temperature wet-chemical method possess several advantages, such as low toxicity, cheap fabrication cost, convenient device processability and adjustable emission wavelengths from ultraviolet to visible and extending to second near infrared window. In addition, they exhibit X-ray excited long persistent luminescence (XEPL) making them suitable for broadening the scope of their applications. This review discusses and summarizes the XEOL and XEPL characteristics of lanthanide doped fluoride NSs. We discuss design strategies and nanostructures that allow manipulation of excitation dynamics in a core–shell geometry to simultaneously produce XEOL, XEPL, as well as photon upconversion and downshifting, enabling emission at multiple wavelengths with a varying time scale profile. The review ends with a discussion of the existing challenges for advancing this field, and presents our subjective insight into areas of further multidisciplinary opportunities.

International audience; Quantum dot (QD)-embedded glass, which is a high-performance multifunctional optical material, has the combined advantages of excellent optical properties of QDs and easy processing of glass. In this study, an inorganic PbS QD embedded multicomponent glass, which produces variable emission at different ultra-violet (UV) excitation wavelengths, is synthesized. The samples are fabricated via a facile melt-quenching method and their structural, optical, photoluminescent, and morphological properties are discussed. The QD glass exhibits broad-band UV excitation in the range of 250-400 nm, and the full width at half max-imum of the emission peaks of the QD glasses reaches 177.8 and 158.5 nm at room temperature under an excitation of 365 and 310 nm, respectively. Notably, white light emission with a high color rendering index is obtained under UV excitation at 350 and 365 nm by doping blue light emitting rare earth (RE) Tm3+ ions into the system. The doped samples exhibit excellent color stability and their CIE coordinates shift along the Planck blackbody locus with increasing temperature. Further, based on the differences in the luminescence mechanisms of the PbS QDs and Tm3+ ions, the application potential of the RE-doped PbS QD-embedded glasses in optical thermometry is discussed. The results demonstrate the application potential of these optically multifunctional inorganic QD glasses in the fields of optical conversion, anti-counterfeiting, white light illumination, and non-contact optical temperature measurement.

A series of Rb

Phosphor is an important part of the new generation of light-emitting diodes (LEDs), which requires high luminous intensity and high-temperature resistance. In this study, a series of excellent (Ba1−x−yCax)AlSi5O2N7:yEu2+ phosphors was developed, which were synthesized by a high-temperature solid-state reaction in a reducing atmosphere. In addition, the crystallinity and luminescence intensity of the samples could be enhanced by some amount of Ca2+ substitution. The luminescence intensity was the highest when the Eu2+ concentration reached 0.06. Furthermore, the thermal stability of the luminescence was studied in detail. The results were satisfactory, showing that the luminescence intensity of the (Ba1−xCax)AlSi5O2N7:Eu2+ phosphors exhibited unique negative-thermal-quenching characteristics both at high (273–473 K) and low (4–273 K) temperatures. And the phosphor combined with UV LED chip and red phosphor Sr2Si5N8:Eu2+ can achieve a CRI of 90.4 in white LED application which indicated the (Ba1−xCax)AlSi5O2N7:Eu2+ phosphor has potential in LED applications.

As is well known, a way to obtain a high color resolution and saturation of a liquid crystal display and thereby obtain a higher visual accuracy and comfort in the coming 5G era remains an urgent challenge. In the present study, a new type of phosphor composite material doped with Ln3+ ions provides a promising alternative to the color filters used in White light-emitting diodes (WLEDs), achieving a better performance regarding the realization of a wider color gamut. The advantages of this composite material are illustrated through an abundant phase and morphology analysis along with a discussion regarding the X-ray photoelectron spectroscopy of the valence bond of Ce ions, which maintain the luminescence properties of the phosphor while providing a stable and solid amorphous environment. An improved spectral performance was obtained through color filtering at 580 nm along with the regulating effects of red, green, and blue emissions according to the doped Ln3+ ions. Notably, we fabricated a high-performance WLED based on a Ln3+-doped PiG with a correlated color temperature of 5037 K, color rendering index of 72.8, and high color gamut of 91.97%, providing a new choice for the development of luminescence materials with a high color resolution and saturation.

Realizing multicolored luminescence in two-dimensional (2D) nanomaterials would afford potential for a range of next-generation nanoscale optoelectronic devices. Moreover, combining fine structured spectral line emission and detection may further enrich the studies and applications of functional nanomaterials. Herein, a lanthanide doping strategy has been utilized for the synthesis of 2D ZnSe:Er

To achieve high-temperature-sensing sensitivity, a new strategy of optical thermometry is designed based on the synergetic luminescence of the radiative emission of lanthanide (Ln) ions and defect-...

Phosphor-in-glass (PiG) is a novel fluorescent color conversion material that is an excellent choice for preparing wide-color gamut white LEDs due to its excellent thermal stability, high efficiency and facile preparation process. To the best of our knowledge, this paper is the first to widen the color gamut of the white LED from 77.33% to 92.02% by doping the PiG substrate with two kinds of lanthanide ions: Er3+ and Nd3+. The low sintering temperature and suitable preparation process has ensured the phosphor and glass become compounded independently together while still exhibiting good luminescence performance; this has been demonstrated via X-ray diffraction and field emission scanning electron microscopy. The influence of doping the host glass with Ln3+ ions has been explored, specifically considering the effects on the color gamut, the color coordination, the correlated color temperature and the color rendering index. The results presented herein have demonstrated that the Er3+/Nd3+-doped PiG is a promising candidate as a color filter in the domain of wide-color gamut white LED.

Ultrathin two-dimensional (2D) materials have drawn great attention in recent years due to their promising applications in biomedicine and atomically optoelectronic devices. In this work, we have fabricated a 2D In2Se3 nanosheet doped with Nd3+ ions via the two-step method of solid phase synthesis and liquid exfoliation. Owing to the special inner 4f-4f energy level transitions, lanthanide ions can emit photons with almost the same energy in different environments. Here, a stable near-infrared luminescence from Nd3+-doped 2D In2Se3 nanosheets has been realized, which includes emission bands around 910, 1057, and 1324 nm. The doping of Nd3+ ions extends the emission region of In2Se3 nanosheets. Moreover, the photoluminescence mechanism of Nd3+ ions was investigated through a series of optical measurements. This work not only provides a reliable method to fabricate lanthanide ion-doped 2D materials but also possesses a great significance for luminescence study of lanthanide ions in the 2D matrix.

Phosphor is an important part of the new generation of light-emitting diodes (LEDs), which requires high luminous intensity and high-temperature resistance. In this study, a series of excellent (Ba

Scintillation-based X-ray excited optical luminescence (XEOL) imaging shows great potential applications in the fields of industrial security inspection and medical diagnosis. It is still a great challenge to achieve scintillators simultaneously with low toxicity, high stability, strong XEOL intensity, and weak afterglow as well as simple device processibility with weak light scattering. Herein, we introduce ethylenediaminetetraacetate (EDTA)-capped NaGdF

Fluorescence intensity ratio-based temperature sensing with a self-referencing characteristic is highly demanded for reliable and accurate sensing. Although enormous efforts have been devoted to explore high-performance luminescent temperature probes, it remains a daunting challenge to achieve highly relative sensitivity which determines temperature resolution. Herein, we employ a novel strategy to achieve temperature probes with ultrahigh relative sensitivity through integrating both positive and negative thermal quenching effect into a hydrogel. Specifically, Er3+ ions show evidently a positive thermal quenching effect in Yb/Er:NaYF4@NaYF4 nanocrystals while Nd3+ and Tm3+ ions in a Yb2W3O12 bulk exhibit prominently a negative thermal quenching effect. With elevating temperature from 313 to 553 K, the fluorescence intensity ratio of Er (540 nm) to Nd (799 nm) and Tm (796 nm) to Er (540 nm) is significantly decreased about 1654 times and increased about 14,422 times, respectively. The maximum relative sensitivity of 15.3% K-1 at 553 K and 23.84% K-1 at 380 K are achieved. The strategy developed in this work sheds light on highly sensitive probes using lanthanide ion-doped materials.

Efficient NIR–MIR luminescence conversion materials are urgently required for numerous applications in the fields of medicine, remote sensing, and optical communications. The control of the chemica...

Non-contact optical thermometry based on fluorescence intensity ratio (FIR) technique has been widely researched over the past few decades. However, the reported systems exhibit two important shortcomings including the existence of a few interferential signals in addition to the required spectral bands for FIR and the absence of internal standard for reference signal. Herein, only two emission bands of Er3+:4F9/2→4I15/2 (~673 nm) and Tm3+:3H4 → 3H6 (~800 nm) are achieved in Yb/Er/Tm tri-doped Na3ZrF7 nano-system. Moreover, the upconversion (UC) emission intensity of Er3+ keeps unchanged with the rising of temperature, which is applied as reference signal; while that of Tm3+ enhances evidently, which is applied as temperature signal. The calculated maximum absolute temperature sensitivity (Sa) and relative temperature sensitivity (Sr) are 0.17 K−1 at 393 K and 1.76% K−1 at 313 K, respectively.

We investigated thermal and fluorescence properties of Er3+ doped fluoroaluminate multi-component glasses modified by TeO2 and CaCl2. A better thermal stability with a higher ΔT (98 °C) was obtained for the TeO2 modified sample, which had a high radiative transition probability (Arad) of the Er3+: 4I11/2→4I13/2 transition. In addition, under 980 or 808 nm excitation, the Er3+ 2.7 µm emission intensity of the TeO2 modified sample decreased owing to its increased hydroxyl content induced by TeO2 modifiers. Excellent mid-infrared fluorescence along with a longer lifetime (3.48 ms) were observed in the glass tuned by CaCl2. The CaCl2 modified sample exhibited higher stimulated absorption and emission cross sections, obtained using the Fuchtbauer-Ladenburg and McCumber formulas. Moreover, the strong effect of hydroxyl on the mid-infrared fluorescence properties was systematically analyzed. The oxygen network modifiers in the fluoroaluminate multi-component glass provide improved thermal properties, while the AlF3-based glasses with chlorine network modifiers have larger potentials for applications in the mid-infrared region.

Cation doping strategy has been extensively employed to enhance the charge carrier mobility and improve the stability of halide perovskites; however, the fundamental understanding of the inherent doping mechanism is still a challenge. Herein, based on a unique four-precursor synthetic strategy and density functional theory (DFT) calculation results, we verify that excessive chloride ion concentration benefits the formation of the bond [Pb⋯Cl] vacancy pair as well as the subsequent incorporation of the [Mn⋯Cl] ion pair synchronously. As a result, high Cl− ion concentration greatly promotes the incorporation of the Mn2+ ions into the CsPbCl3 crystal lattice. The particle size reduction of the CsPbCl3 perovskite with the incorporation of the Mn2+ ions is attributed to the increased surface electron charge density, which inhibits the diffusion of the negatively charged Cl− ions to the nuclei surface. These deep insights into the inherent Mn2+ doping mechanism could guide the realization of novel ion-doped perovskites with new optoelectronic performances.

Diode-pumped solid-state 2 μm lasers have seen rapid development for their efficient operation, compact size, and stable performance. In this work, doped germanosilicate (SiO2-GeO2-Ga2O3-Lu2O3) glasses with varying Tm3+/Ho3+ concentrations exhibiting excellent physical and optical characteristics were successfully prepared. Thermal and structural properties were analyzed by the measured DSC and Raman spectra. An evident efficient wide absorption band near 770–830 nm demonstrated the feasible energy transfer between Tm3+: 3F4 → 3H6 and Ho3+: 5I7 → 5I8 transitions. Meanwhile, combining with Judd-Ofelt theory, super predicted spontaneous emission probabilities were obtained, which are beneficial to obtain fine laser action for solid-state lasers. This is a first study to demonstrate that a tunable fluorescence peak (1.8–2.05 μm) can be obtained by modulating the combined effects between two luminous activation centers. Therefore, the results indicate a promising rare-earth doped glass host for solid-state 2 μm lasers.

The surface plasmon resonance (SPR) of metal nanostructures is known to affect the optical properties of solid luminescent materials. Ag nanoparticles were first used to obtain a wider color gamut in rare-earth-doped phosphor-in-glass for application as color filters for white light emitting diodes. The existence of Ag nanocrystallites at nanometer scale and the independent integrity of the phosphor luminescence center in the amorphous glass environment were demonstrated. Using UV–Vis spectroscopy, the localized SPR absorption band was observed at 480 nm, and the optical properties of the nanostructures were found to be dependent on the annealing temperature. Hence, an expansion of the color gamut from 79.07% to 93.31% was realized by the coefficient effect of N d 3 + active ions and Ag nanoparticles. These results suggest that N d 3 + -ion-co-doped phosphor-in-glass modified by Ag nanoparticles could be potentially applied as a novel optical material with a wide color gamut.

Surface-enhanced Raman scattering (SERS) has attracted much attention with its powerful trace detection and analysis capabilities, especially biological and environmental molecules. However, building a protein SERS detection platform based on semiconductor devices is a huge challenge. Herein, through the synergy of NH3 and nickel foam, a large-sized semiconductor tungsten oxide hydrate platform (WOHP) was synthesized. The crystal plane of a single WOHP particle is larger than the excitation spot. As a SERS substrate, WOHP can make full use of the excitation light without destroying the structure during the protein molecules detection process. Through the synergy of WOHP and Au NPs, the enhancement factor is 1.5 × 104. Raman peaks of WOHP can be used as references for the detection of typical protein cytochrome C (Cyt C). As the Cyt C concentration decreases, the ICyt C/IWOHP ratio decreases, and the signal can still be obtained when the concentration is as low as 5 × 10−9 mol L−1. More importantly, the method does not affect the catalytic activity of Cyt C and can be applied to the detection of Cyt C concentration in serum.

The development of integrated multifunctional materials with transparent characteristics meets the requirements of optoelectronics and communication. The coupling of stimuli-responsive materials has become a frequently considered strategy. Experimentalists not only search for photonic materials with excellent physical and chemical properties, but also pursue precise and reversible spectral modification. In this study, the luminescent center Ni2+ is artificially introduced into the transparent LiNbO3 nanoferroelectric photonic materials. The Ni2+ ion-based transparent photonic materials exhibit novel complete ultra-broadband emission in the whole near-infrared region. Until now, the ultra-broadband emission was realized by codoping of several active doping ions. In addition, the emission intensity and wavelength of the luminescent center are modified accurately and reversibly by field-induced nanoscale structural transformation. The Ni2+ ion-based transparent nanoferroelectric photonic materials provide an easy way to develop tunable lasers and ultra-broadband optical amplifiers.

As a leader of long persistent luminescence (LPL) materials, the optical properties of aluminate phosphor have remained unsurpassed for many years. As a powder material, its practical application will always be limited to the field of security signs. In this paper, the SrAl 2 O 4 : Eu 2 + , Dy 3 + inorganic solid material with comparable LPL properties to powder materials was obtained. The crystallization mechanism and crystallite micro-morphology of inorganic glass materials have been studied, and a new opinion is put forward that the large-size SrAl 2 O 4 crystallites in the glass matrix are stacked by rod-shaped crystals arranged in a regular direction. In addition, the SrAl 2 O 4 : Eu 2 + , Dy 3 + glass obtained cannot only collect high-energy photons but also is sensitive to low-energy sunlight. The results show that the material exhibits superior performance in LPL, thermoluminescence, and photostimulable luminescence. Based on this property, a new application of this material in the field of information storage was explored. This paper has a certain reference value for the development and application of aluminate LPL materials in the field of smart optical information storage.

Highly rare earth（RE）ions doped glass laser materials can produce efficient single frequency mid-infrared laser. In this work, a series germanosilicate glasses with various high erbium-doping concentration (up to 4 mol%) and without concentration quenching are fabricated. Spectroscopic properties and energy transfer (ET) mechanism of efficient Er3+:4I11/2 →4I13/2 transition have been investigated in detail upon a conventional 980 nm Laser Diode. The dense structure of silicate glass can be dissolved effectively by the introduction of GeO2, which was analyzed by Raman spectra, so that the compatibility and luminous intensity of RE ions were improved. The high predicted spontaneous transition probability (Arad = 37.65 s−1) based on the Judd-Ofelt theory and large calculated emission cross section (8.8 × 10−21 cm2) are obtained. The above results indicate that these glasses are promising to be the single frequency mid-infrared laser material.

It was reported that the UC emission intensity can be improved by introducing a thermal field and this phenomenon is highly related to the Yb3+ ions. Herein, we verify the thermal-induced UC enhancement degree can be further increased by separating the Yb3+ ions in the core and shell to promote the population of the defect energy level and inhibit the back energy transfer from Ho3+ to Yb3+ ions.

Recently, rare-earth-doped infrared (IR) luminescent glasses have drawn massive attention due to their potential applications in military, medical, and communications fields. In this Letter, we present a system of oxychloride Si-Ge-O-Cl glasses, suitable for rare-earth doping, which has been developed as a new, to the best of our knowledge, choice for IR luminescent materials. Raman spectra show a looser glass network because of the decreased phonon energy and density compared to the one in heavy-metal oxide glasses. The enhanced luminescence from the visible to the IR region has been obtained with a beneficial fluorescence decay time. The spectroscopy results indicate that the system of Si-Ge-O-Cl glasses may be a promising candidate for application in infrared laser materials with enhanced luminescence.

We report a detailed spectroscopic investigation of a series of fluorotellurite glasses with different Er3+ ions concentration in system 50TeO2-27BaF2-9ZnF2-8YF3-3MgF2-3NaF-xErF3-1HoF3(x = 1,2,3 mol%). Intense 2 μm emission and 2.75 μm emission with high absorption and emission cross-section were observed under 980 nm LD pumping, and the maximum gain coefficient around 2750 nm was as high as 2.41 cm−1, suggesting the prepared glasses are a competitive candidate for mid-infrared laser materials. Besides, it was found that the trend of 2 μm and 2.75 μm emission intensity varied with Er3+ ions concentration was different. Energy transfer process was discussed subsequently to explain this phenomenon. Furthermore, we quantitatively investigate the energy transfer efficiency from Er3+: 4I13/2 level to Ho3+: 5I7 level.

Bi can exist in a variety of chemical states (with varying ionic charges) and the microstructure of the glass surrounding the ions can be engineered to manipulate the chemical state. In this work, efficient enhancement of Ho3+ emission is observed with the change in local glass environment around Bi by adding Al2O3 to multi-component germanosilicate glass. In this multi-component glass, Al3+ can form tetrahedral AlO4 by accepting the non-bridging oxygen (NBO) and then, the addition of the AlO4-tetrahedron to the glass network facilitates the diffusion of alkali metals. Hence, Al2O3 decreases the Ba2+-rich domain and is conducive to the existence of Bi ions that are at low valence state. Moreover, the emission spectra indicate high efficiency energy transfer (ET) derived from NIR emission centers (Bi0/Bi+) located in close proximity to the Ho3+ ions. These results indicate that the optimized fluorescence of Ho3+ for optical fiber laser can be achieved by adjusting the local structure of the host glass.

White light-emitting diodes (LEDs), as a fourth-generation green lighting source, have been widely used in various fields. At present, most white LEDs have based on a mixture of silicone with poor heat resistance and phosphors as luminescent components, which prevent them from adapting to high-temperature environments and limit their applications of high-power lighting. To improve the optical properties and reliability of white LEDs, phosphor solid is proposed as a new alternative, which not only has the strong stability of glass, but also completely retains the luminescent properties of phosphor. Therefore, in this study, tellurite glass was used as the matrix of phosphor solids to improve the luminescence performance by optimizing the composition of the matrix glass. In addition, rare earth ions were introduced into the tellurium glass matrix, and the dissolution ability of the matrix to rare earth ions was explored to improve the luminous quality of white LEDs.

A series of β-Sr1.98-yMgySiO4-1.5xNx: 0.02Eu2+ (x = 0, 0.3, 0.6, 0.9, 1.2 and 4/3, 0 ≤ y ≤ 0.5, β-S(M)SON: Eu2+) phosphors were synthesized by a conventional solid state reaction method. The coordination environments of Eu2+ are modified effectively via the introduction of N3- and Mg2+ using different concentration, which is confirmed by XRD refinement results and PL spectra. Both fourier transform infrared (FT-IR) spectra and energy dispersive spectroscopy (EDS) analysis qualitatively confirm that the existence of N3-. The crystal structures of β-Sr2SiO4-1.5xNx (β-SSON): Eu2+ and β-Sr2-yMgySi(O,N)4: Eu2+ (β-SMSON, x = 4/3, y = 0.1) have been determined effectively. Rietveld refinement indicates that N3- dopants most likely partly substitute O22− site. With the increase of N content, the unit cell volume and partial Si O and Sr N bond lengths gradually decrease, which are coincided each other. With the introduction of N3-, the emission of Eu(I) (∼465 nm) hardly change but that of Eu(II) (∼540 nm) splits into two emission bands as Eu(II) (∼540 nm) and Eu(II)′ (∼616 nm). According to the analysis of XRD data, unit cell volume, FT-IR spectra, photoluminescence (PL) and reflectance spectra of β-SMSON: Eu2+, it can be concluded that the incorporation of Mg2+ into the host leads to interstitial sites rather than substitutional ones. Mg2+ doping couldn't change the dominant peak wavelengths (DPWs) of Eu(I), Eu(II) and Eu(II)′ sites but only affects the PL intensity of title phosphors and could offset the nitridation effects. The concentration quenching mechanism and thermal activation energy of β-SSON: Eu2+ phosphors are determined effectively. The β-S(M)SON: 0.02Eu2+ phosphor have the feature that it can achieve color-tunable white light-emitting combined with blue light emitting diodes (LEDs) with single activator doped and single-phase host, which enables these materials to be enormous possibilities used in white light emitting diodes.

A novel tunable red to yellow emitting phosphor, (Ca, Ba) 4 (PO 4 ) 2 O:Eu 2+ is reported that displays a broad emission from 500 to 800 nm, and its emitting color can be adjusted from red to yellow by changing Ba 2+ doping concentration. X-ray powder diffraction (XRD) analysis confirmed the phase formation. Excitation and emission spectra, and concentration dependence of emission intensity of the phosphor were investigated. The results showed that the emission peak wavelength take blue-shifted from 640 to 545 nm and the color hue can be tuned from red to yellow with increasing Ba 2+ concentration. When single-phase (Ca 3.85 Ba 0.10 )(PO 4 ) 2 O:0.05Eu 2+ phosphor is pumped by a blue InGaN light-emitting diode, we obtain white light with color rending index ( R a ) between 84.0 and 90.6 and color temperatures between 4000 and 5500 K, which suggests that this material is competitive as a color conversion material for solid state lighting.

Phosphor-in-glass (PiG) is a novel fluorescent color conversion material that is an excellent choice for preparing wide-color gamut white LEDs due to its excellent thermal stability, high efficiency and facile preparation process. To the best of our knowledge, this paper is the first to widen the color gamut of the white LED from 77.33% to 92.02% by doping the PiG substrate with two kinds of lanthanide ions: Er

A series of fluorophosphates glass codoped with active Er

Rare-earth-doped optical functional glasses have attracted great interest for their excellent luminous performance in the applications of optical communications and biomedical systems. To the best of our knowledge, it is demonstrated for the first time that more than seven times' enhancement of luminescence performance in the mid-infrared region (MIR) has been obtained in germanosilicate glasses controlled by ZnF

Metal-organic framework (MOF) glasses are a newly discovered family of melt-quenched glasses. However, so far it is not known whether these glasses exhibit photonic functionalities. Here, we show the discovery of the luminescent behavior of a MOF glass, i.e., the cobalt doped zeolitic imidazolate frameworks-62 (ZIF-62) glass (Zn1-x Cox (Im)1.9 (bIm)0.1, x = 0, 0.1 and 0.5), which was obtained by melt-quenching its corresponding ZIF-62 crystal. The synthesized crystal was precipitated in the form of spherical nano/micro-crystalline structure, which collapses structurally to form laminated glass with ultrahigh glass forming ability and the same short range molecular structure of the parent crystalline MOF. We observed the super-broadband mid-infrared (Mid-IR) luminescence (in the wavelength range of 1.5 µm – 4.8 µm) both in the crystalline and amorphous phases. The observed Mid-IR emission originates from d-d transition of Co2+ ions that is protected by the strong Co-N coordination. The discovery of the luminescent glasses may pave the way towards new photonic applications of bulk MOF glasses, such as Mid-IR lasers.

A series of novel blue-emitting Ba1-xAl2Si3O4N4: xEu2+ phosphors were successfully prepared by two-steps high temperature solid state reaction. The results of XRD and SEM showed that the two-steps method obtain less impurities than the traditional one-step method. The electronic band structure of BaAl2Si3O4N4 (BASON) host was calculated as a direct band gap of 3.662eV by the DFT method. The PLE spectrum of B1-xASON: xEu2+ showed a wide band excitation in the wavelength range of 250–450 nm, which can be well matched with n-UV chips. Based on crystal structural and fluorescence lifetime analysis, three emission peaks were obtained by gaussian fitting to explain the asymmetry of Eu2+ emission in the BASON phosphor. The optimal doping concentration of Eu2+ was x = 0.04. According to calculated critical distance (3.24 A) and a little overlap between PLE and PL spectra, the concentration quenching mechanism was confirmed as both of dipole-dipole interaction and radiation reabsorption. In addition, with the incorporation of Eu2+, the diffuse reflection spectrum of B1-xASON: xEu2+ presented a wide absorption peak in the range of 200–500 nm. The PL intensity of Ba0.96-ySryAl2Si3O4N4: 0.04Eu2+ tended to rise first and then fall with the increase of Sr2+ concentration. Impressively, the relative emission intensity at 473K still maintained 95.7% compared with room temperature (293K), which indicated the excellent thermal stability of BASON phosphor. Finally, the density of state (DOS) of Ba1-ySryAl2Si3O4N4 (y = 0, 0.5, 1) were calculated and analyzed to explain the deterioration of thermal stability with the increase of Sr2+ substitution.

A series of single-phase white-light-emitting phosphors, Eu 2+ -activated Ba 3 GdNa(PO 4 ) 3 F phosphors were synthesized by solid-state reactions. The crystal structure of Ba 3 GdNa(PO 4 ) 3 F was been identified by Rietveld refinement of X-ray diffraction pattern. The Eu 2+ -activated Ba 3 GdNa(PO 4 ) 3 F phosphors exhibit broad excitation spectra from 250 to 420 nm, which matched well with the n-UV LED chips. Under the excitation of 365 nm, the emission spectrum almost covered the entire visible region including two emission bands peaked at 472 nm and 640 nm. Three different Eu 2+ emission centers in Ba 3 GdNa(PO 4 ) 3 F:Eu 2+ phosphor were confirmed by their fluorescence decay lifetimes. The optimal concentration of Eu 2+ in Ba 3 GdNa(PO 4 ) 3 F: x Eu 2+ was 3 mol% and the corresponding concentration quenching mechanism was verified to be exchange coupling interaction. Furthermore, the white light-emitting diode fabricated with Ba 3 GdNa(PO 4 ) 3 F:0.05Eu 2+ phosphor and a 370 nm UV chip has a CIE of (0.3267, 0.2976) with a color-rendering index of 78.4 at the CCT of 5287 K.