Integrated Emission Intensity Research Articles

Effects of Two Different Size ZnO Nanoparticles on the Growth of Aspergillus oryzae

Two different kinds of ZnO nanoparticles (NPs) with distinct particle sizes were synthesized by a precipitation method. For the first time, the effects of two distinct sizes ZnO NPs on the growth, photoluminescence properties and kojic acid (KA) yield of Aspergillus oryzae (A. oryzae) were examined. The findings showed that ZnO-A and -B NPs, with average particle sizes of 11.93 nm and 34.41[Formula: see text]nm, respectively, exhibited a hexagonal crystal structure. It was found that when the concentration of NPs was below 100[Formula: see text][Formula: see text]g/mL, ZnO NPs were nontoxic and served as activators to stimulate the growth of A. oryzae, and the biomass of solid and liquid medium, the total integral emission intensity, the content of extracellular protein and total organic carbon and KA yield of A. oryzae grown with ZnO-A (ZnO-B) NPs were about 2.19 (1.97), 2.47 (1.56), 1.67 (1.16), 2.45 (1.95), 0.47 (0.50) and 2.07 (1.37) times more than that of control sample (without NPs), respectively.

Remarkable broadband NIR emission of BaCa2MgSi2O8:Cr3+ phosphors and Eu2+ co-doping modulation

Developing high-performance broadband NIR (near-infrared) phosphors remains a crucial pursuit for the next-generation smart NIR light source. This study demonstrates the successful synthesis of BaCa2MgSi2O8:Cr3+ phosphors exhibiting exceptional broadband NIR emission via a high-temperature solid-state reaction. Notably, the 0.03Cr3+ doped composition, under 485 nm excitation, shines with a remarkable broadband emission spanning 700 nm–1100 nm and boasts a full width at half maximum (FWHM) of 134 nm. This work meticulously explores the intricate interplay between Cr3+ doping concentration, temperature, crystal field strength, and the Huang-Rhys parameter, shedding light on the underlying luminescence mechanisms. Moreover, the BaCa2MgSi2O8:0.03Cr3+ phosphor exhibits exceptional thermal stability, retaining approximately 70 % of its integrated emission intensity at 425 K compared to room temperature. To further expand the excitation range, Eu2+ was introduced as a co-dopant, successfully broadening the excitation spectrum to encompass nearly the entire ultraviolet–visible region (ranging from 250 nm to 750 nm). The presence of Eu2+→Cr3+ energy transfer was elucidated, and the impact of Eu2+ doping was thoroughly investigated. Moreover, the synthesized phosphor has been successfully integrated into a NIR phosphor-converted light-emitting diode (pc-LED), showcasing their potential application in the realms of night vision and NIR vascular imaging. These findings offer invaluable insights into Cr3+ luminescence behavior and pave the way for the development of novel NIR phosphors with enhanced functionalities, propelling us closer to the realization of next-generation smart lighting solutions.

Near-infrared optical properties of Cs2KScF6:Cr3+ phosphor for high-power light-emitting diodes

The recent years have witnessed a great leap for near-infrared (NIR) spectroscopy technology in multifunctional application fields. In this study, a double-perovskite structured Cr3+-doped Cs2KScF6 fluoride NIR phosphor with peak location at 778 nm and full-width at half maximum (FWHM) of 95 nm was synthesized by a co-precipitation method. The integral emission intensity at 423 K retains 70 % of that at room temperature (RT), showing good luminescent thermal stability. Combining the obtained phosphor in an NIR phosphor converted light-emitting diode (NIR pc-LED) device, the output power and photoelectric conversion efficiency can reach 72.28 mW and 6.83 % at 320 mA. By virtue of the good optical performance, clear structural images of different fruits were visualized by using the NIR pc-LED as light source, suggesting the potential of Cs2KScF6:Cr3+ phosphor to be used in high-power LED devices.

Striking antithermal quenching and waterproofness of Mn4+-doped fluoride phosphors induced by synergy of double coating and single passivation

Manganese (IV) (Mn4+)-doped fluoride phosphors generally suffer two pressing problems, thermal quenching (TQ) and poor water resistance. This study reports striking luminous intensity enhancement, anti-TQ property, and waterproofness of Mn4+-doped potassium fluosilicate phosphors induced by synergy of double coating and single passivation (coating with hydroxylated graphene quantum dots (GQDs), passivation with H2O2, and coating with K2SiF6). The luminous intensity of the phosphor is approximately 163 % of that of K2SiF6:Mn4+. The integrated emission intensity at 150 °C is 129.3 % higher than that at 30 °C. The emission intensity remains 93.2 % of the initial value after immersion in water for 480 min. These results are attributed to energy transfer from GQDs to Mn4+ and the formation of a stable Mn-free shell layer. In particular, the white light-emitting diodes produced using the phosphors maintained 99.6 % luminescence efficiency after 240 h of operation in high-temperature, high-humidity environments. We believe that this study provides a feasible approach to simultaneously enhance the thermal stability and waterproofness of Mn4+-doped fluoride phosphors.

Broadband NIR phosphor Gd3Lu2Ga3O12: Cr3+, Yb3+ with high thermal stability

Broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have become important as new NIR light sources in NIR spectroscopy and NIR imaging techniques. However, currently developed broadband NIR phosphors commonly suffer from weak emission and poor thermal stability. In this work, a series of Gd3Lu2Ga3O12: Cr3+ phosphors were synthesized via high-temperature solid-state reaction. Under 460 nm excitation, the phosphors exhibit an intense emission spanning from 650 to 1150 nm with a full width at half maximum (FWHM) of 122 nm. After introducing Yb3+ as a co-dopant, the emission of the phosphor has been broadened greatly. Interestingly, the studied phosphors demonstrate super high thermal stability in a wide temperature range of 35–560 K, with the integrated emission intensity fluctuating within 10 %. At 435 K, the emission intensity of Gd3Lu2Ga3O12: 0.03Cr3+ remains 99.5 % and Gd3Lu2Ga3O12: 0.03Cr3+, 0.01 Yb3+ keeps 102.7 % of the initial intensity at room temperature. These NIR phosphors have been encapsulated with a common commercial 460 nm blue LED chip to fabricate a pc-LED device. The NIR output power of the device reaches 23.93 mW@100 mA, with a photoelectric conversion efficiency of 9.81 % at 20 mA current. The applications of the prepared NIR light source in night vision, and bioimaging have been demonstrated. The results show that these Cr3+/Yb3+ doped garnet phosphors can be effectively used in NIR light sources.

Cr3+ activated Gd3Sc2Al3O12 garnet phosphor ceramic with broadband emissions and enhanced thermal stability toward high-power near-infrared LED/LD

The development of high-quality phosphor ceramics with high photoelectric efficiencies and thermal stabilities is essential for realizing high-power broadband near-infrared light sources. In this study, a series of pure-phase Gd3Sc2Al3O12:Cr3+ near-infrared (NIR) phosphor ceramics (GdScCr NIR-PCs) exhibiting remarkable thermal stability and broadband emission were fabricated for the first time using a vacuum sintering technique. The integrated emission intensity at 423 K is 79.8 % of that at room temperature. The GdSc08Cr exhibits an emission peak at a wavelength of 785 nm, with a full width at half maximum (FWHM) of 116.9 nm under 460 nm excitation. By integrating the GdScCr NIR-PC with a blue light-emitting diode/laser diode (LED/LD) excitation source, the NIR LED prototype achieved a maximum output power of 112.19 mW at 300 mA with a photoelectric conversion efficiency of 13.64 % at 150 mA, and the NIR LD prototype achieved a maximum power output of 484.34 mW at 2.3 A. The operating temperatures of NIR-PCs were 73.1 °C at 300 mA for LED and 90.7 °C at 2.5 A for LD. Moreover, the application of the prepared GdScCr NIR-PCs for fruit and grain detection was performed. These results demonstrate that the prepared GdScCr NIR-PCs possess substantial potential for application in high-power broadband NIR spectroscopy.

UVC Up-Conversion and Vis-NIR Luminescence Examined in SrO-CaO-MgO-SiO2 Glasses Doped with Pr3.

The application of ultraviolet-C light in the field of surface treatment or photodynamic therapy is highly prospective. In this regard, the stable fluorescent silicate SrO-CaO-MgO-SiO2-Pr2O3 glasses able to effectively convert visible excitation on the ultraviolet praseodymium emission were fabricated and examined. An unusual wide-range visible-to-UVC up-conversion within 240-410 nm has been achieved in Pr3+-doped glasses, revealing their potential advantage in different sophisticated disinfection technologies. The integrated emission intensity was studied as a function of light excitation power to assess a mechanism attributed to UVC luminescence. Especially, it was revealed that the multicomponent silicate glass qualities and praseodymium 3PJ excited state peculiarities are favorable to obtaining useful broadband ultraviolet up-converted luminescence. The glass dispersion qualities were determined between 450-2300 nm. The impact of praseodymium concentration on Vis-NIR spectroscopic glass qualities was evaluated employing absorption spectra, emission spectra, and decay curves of luminescence associated with two involved praseodymium excited states. Especially, efficient interionic interactions can be inferred by investigating the decrease in 1D2 state experimental lifetime in the heavily doped samples. Examination of absorption spectra as a function of temperature implied that excitation at 445 nm should be quite effective up to T = 625 K. Contrary to this, temperature elevation gives rise to a moderate lowering of the visible praseodymium luminescence.

Ce3+-Activated SrLu2Al3ScSiO12 Cyan-Green-Emitting Garnet-Structured Inorganic Phosphor Materials toward Application in Blue-Chip-Based Phosphor-Converted Solid-State White Lighting.

Phosphor-converted white-light-emitting diodes (WLEDs) with superhigh color rendering index (CRI) are the ongoing pursuit of next-generation solid-state lighting. One of the most important challenges is the limited improvement in CRI on account of the absence of a cyan component in the typical commercial combination. Here, a bright broad-band cyan-green-emitting phosphor with cubic garnet structure, SrLu2Al3ScSiO12:Ce3+ (SLASSO:Ce3+), was successfully reported, which can compensate for the absence of cyan cavity in the 480-520 nm blue-green emission region. With 439 nm blue-light irradiation, the as-fabricated SLASSO:Ce3+ phosphor yields a broad-band cyan-green emission with the maximum emission peak positioned at 525 nm and an appropriate full width at half-maximum (fwhm) of 111 nm, capable of providing more cyan emission component without sacrificing green emission. Meanwhile, the optimal SLASSO:2%Ce3+ phosphor features CIE color coordinates of (0.3254, 0.5470) with cyan-green hue, along with a high internal quantum efficiency of up to 93%. Additionally, thermal stability measurements at different temperatures reveal that the luminescence emission intensity of the proposed phosphor retains 44% of its original integral emission intensity at 423 K with respect to room temperature, while also demonstrating an excellent color stability (ΔE = 5.4 × 10-3). This work shows that the highly efficient SLASSO:Ce3+ garnet phosphor can be utilized as a potential cyan-green-emitting phosphor for filling the cyan gap, resulting in the construction of a high-quality warm WLED with high CRI for "human-centric" sunlight-like full-spectrum solid-state illumination.

Scintillation and photoluminescence performance of Ce3+-doped high gadolinium oxyfluoride glass for circular electron-positron collider (CEPC)

The large size (4 cm × 4 cm × 1 cm) Ce3+-doped high gadolinium oxyfluoride glass with density of 5.83 g/cm³ was prepared by the melt quench method at 1220 °C. The glass is colorless and transparent over the visible range. The prolonged decay time under 275 nm UV light demonstrates the energy transfer from Gd3+ ions to Ce3+ ions. The X-ray excited luminescence spectra (XEL) show the emission peak corresponds to the 5d→4f transitions of Ce3+ ion. The integral emission intensity of glass was compared with that of bismuth germanate oxide (BGO) crystals. The scintillation property of glass was studied under the γ-ray from 137Cs source and a clear energy peak was observed with light yield (LY) over 1100 ph/MeV. The scintillation decay time comprises fast and slow components. All results presented in this work indicate the appropriate potential to be high-energy rays detecting material for CEPC.

Nanocrystals Incorporated with Mordenite Zeolite Composites with Enhanced Upconversion Emission for Cu2+ Detection.

In this research, upconversion nanocrystals incorporated with MOR zeolite composites were synthesized using the desilicated MOR zeolite as a host for the in situ growth of NaREF4 (RE = Y, Gd) Yb/Er nanocrystals. The structure and morphology of the composites were studied with XRD, XPS, and TEM measurements, and the spectral studies indicated that the subsequent thermal treatment can effectively improve the upconversion emission intensity of Er3+. By using the NaYF4:Yb/Er@DSi1.0MOR-HT composite that holds the strongest upconversion emission, a probe of UCNC@DSiMOR/BPEI was constructed with the modification of branched poly ethylenimine for the detection of Cu2+. It was indicated that the integrated emission intensity of Er3+ shows a linear dependence with the logarithm value of the Cu2+ concentration ranging from 0.1 to 10 μM. This study offered a feasible method for the construction of UCNC@zeolite composites with enhanced upconversion emission, which may have a potential application as fluorescent probes for the detection of various metal ions by adjusting the doping luminescent center.

Fluorescence Resonance Energy Transfer Study Between ZnS Quantum Dots and Fluoranthene

AbstractSingle‐phase zinc sulphide (ZnS) quantum dots were synthesized by hydrothermal method without using any capping agent. X‐ray power diffraction, transmission electron microscopy, and ultraviolet‐visible spectroscopy were used to characterize the structure, size, surface states. Photoluminescence properties of ZnS quantum dots were studied to apply it as fluorescence sensor. The results showed that the crystal structure of ZnS quantum dots was a cubic zinc blende, and their average diameter was about 3.5 nm. A strong broad band cantered at about 320 nm was observed in the excitation spectrum of ZnS quantum dots. Their emission spectrum peaking at about 408 nm, was due mostly to the trap‐state emission. We used cadmium as fluorescence super quencher to detect the presence of cadmium. The relative integrated emission intensity of ZnS quantum dots decreased as the amount of Cd increased. That 408 nm emitted radiation was then used to detect the presence of fluoranthene, a potential carcinogen, present in solution. The novelty of the process is the use of water as a solvent for synthesis, without using any capping agent by slow hydrothermal process.

Thermally Stable NIR Emission from Disordered Ba5La3MgAl3O15:Cr3+ with Peak Wavelength Beyond 900 nm

AbstractBroadband near‐infrared (NIR) emissions in the long wavelength region with simultaneous high efficiency and thermal stability are desirable for NIR phosphor‐converted light‐emitting diodes (NIR pc‐LEDs) light sources. Herein, a novel broadband NIR‐emitting phosphor is reported, Ba5La3MgAl3O15:Cr3+ (BLMAO:Cr3+), which exhibits a NIR emission band spanning 700–1300 nm with maximum peak wavelength (λmax) at 925 nm and full width at half maximum of 160 nm. The optimized phosphor achieves an internal quantum efficiency of 66%, and the integrated emission intensity at 423 K remains 61% of that at room temperature, which surpasses most Cr3+‐activated phosphors emitting in the long‐wavelength NIR region (λmax > 900 nm). The NIR luminescence properties are elucidated on the basis of density functional calculations of the multiple Cr3+ local structures as generated by the Ba/La occupation disorder in the host material. The applications of the NIR phosphor in pc‐LED devices are demonstrated, showing potential in night‐vision and nondestructive examination. The results indicate that BLMAO:Cr3+ is a promising phosphor with highly efficient and thermally stable broadband NIR emission for NIR LED light sources.

A novel borate phosphor Lu5Ba6B9O27:Ce3+ codoped with Sr2+/Tb3+ for NUV-white light emitting diode application.

At present, there are still challenges in developing highly efficient and thermally stable phosphors for ultraviolet/near ultraviolet-white light emitting diodes (UV/NUV-WLEDs). Herein, we use traditional high-temperature solid-state reactions to prepare blue-emitting phosphors Lu5-xBa6B9O27:xCe3+ (0.1% ≤ x ≤ 3.0%) and Lu4.975Ba6-ySryB9O27:0.5%Ce3+ (0% ≤ y ≤ 20%), and green-emitting phosphors Lu4.975-zBa6B9O27:0.5%Ce3+,zTb3+ (0% ≤ z ≤ 16%), abbreviated as LBB:xCe3+, LBB:0.5%Ce3+,ySr2+ and LBB:0.5%Ce3+,zTb3+, respectively. Upon 340 nm excitation, LBB:Ce3+ exhibits an asymmetric blue emission ranging from 360 nm to 480 nm. Furthermore, the emission intensity of LBB:0.5%Ce3+ increased 4.8-fold without a spectral shift through the partial substitution of Sr2+ for Ba2+. Through constructing the Ce3+ → Tb3+ energy transfer in the LBB structure, the temperature-dependent integral emission intensity at 483 K improved from only 25% to 68% of the intensity at 303 K due to the existence of fast energy transfer from Ce3+ to Tb3+. The related results indicate that LBB:xCe3+, LBB:0.5%Ce3+,ySr2+ and LBB:0.5%Ce3+,zTb3+ phosphors can be used for UV/NUV-WLEDs.

Novel YAGG: Cr garnet phosphor ceramic with broadband near infrared (NIR) emission and luminescence thermal stability for plant growth

In recent years, NIR (Near-Infrared) phosphor-converted LEDs (pc-LEDs) have played an indispensable role in the field of plant lighting. This study presents the development of a novel garnet-based phosphor ceramic, YAGG:0.035Cr3+, obtained through a high-temperature solid-state method. Through optical and structural performance analysis, it was found that the sample can be effectively excited by a commercial 450 nm blue LED, emitting near-infrared light in the range of 650–850 nm. This emission spectrum overlaps with approximately 74% of PFR spectrum absorbed by plant growth, and it achieves QY of around 40%. Notably, this ceramic demonstrates excellent thermal luminescence properties, maintaining approximately 96% of its integrated emission intensity at 423 K compared to room temperature. To explain this outstanding thermal performance, we analyzed that the gradual substitution of the 4T2 level for the 2E level leads to the dominance of the 4T2-4A2 transition process in PL. Furthermore, the YAGG:0.035Cr3+ phosphor ceramic was packaged with a 450 nm LED, and the emitted light intensity exhibited a linear relationship with the driving current. Even under high-power driving conditions of 1000 mA, the luminescence did not reach saturation. These results effectively demonstrate the potential application of YAGG:0.035Cr3+ phosphor ceramic in the field of plant lighting.

Synthesis, luminescence properties, and thermal decomposition kinetics of NH4GdF4:Eu3+ with an intense negative thermal quenching effect

Developing Eu3+-doped red emission phosphors with exceptional luminescence thermostability is crucial for advancing white light emitting diodes (WLEDs). Herein, a series of NH4GdF4:xEu3+ (NGF:Eu3+) compounds are synthesized using the co-precipitation method, with NGF:0.25Eu3+ identified as the most promising sample. The paper discusses the mechanism underlying the negative thermal quenching (NTQ) effect, indicating that NGF:0.25Eu3+ exhibits sufficient luminescence thermal stability and chemical resistance under the operational temperatures of WLEDs, making it a viable application for this purpose. Experimental results reveal the following key findings. (a) Supported by the NTQ effect, NGF:0.25Eu3+ exhibits remarkable luminous thermostability. The integrated emission intensities at 150 °C, 180 °C, and 121 °C are 210.6 %, 234.1 %, and 244.2 % respectively, of the initial intensity at 30 °C. (b) NGF:0.25Eu3+ demonstrates good chemical thermostability and sufficient luminescent thermal stability under WLED operational temperatures and commences decomposition at 200 °C, making it suitable for use in WLEDs. (c) An assembled prototype WLED combining NGF:0.25Eu3+ and YAG:Ce3+ (a yellow emitting phosphor), emits warm white light under ultraviolet excitation. Furthermore, this study delves into the thermal decomposition kinetics of NGF:0.25Eu3+ using an iterative approach, identifying a single-step reaction mechanism. Consequently, the study provides three kinetic parameters (Eα, g(α), and A) and three thermodynamic functions (ΔH#, ΔS#, and ΔG#) associated with the decomposition process.

Selective enrichment strategy induces ultra-broadband NIR emission in Cr3+-doped multi-phase glass-ceramics for NIR spectroscopy applications

Near-infrared (NIR) spectroscopy has gained widespread application in food analysis, disease diagnosis, fingerprint analysis, and security monitoring. However, the lack of efficient, broadband NIR luminescent materials hinders the full potential of this technology. Here, an ultra-broadband and high-efficiency Cr3+-doped multi-phase glass-ceramics containing MgAl2O4, Al2SiO5, and SiO2 nanocrystals was discovered, which exhibited an ultra-broadband NIR emission (λem ∼ 900 nm) with a full width at half maximum more than 300 nm and a high internal quantum yield of 50.9% under the excitation of 465 nm blue light. Moreover, the integrated emission intensity at 100 °C and 150 °C can keep 88% and 77% of that at room temperature. The ultra-broadband, high efficiency, and thermally robust luminescence of this Cr3+-doped multi-phase glass-ceramics can be attributed to the selective enrichment of Cr3+ ions into different nanocrystals with octahedral sites, and medium electron-photon coupling effect. The NIR glass-ceramics-converted light-emitting diode constructed by the glass-ceramics combined with 465 blue LED chip produced an excellent NIR output and photoelectric conversion efficiency of 274 mW/1007 mW and 3.43%/2.79% at 100 mA/320 mA drive current, which demonstrated superior overall performance to the NIR device built by using the well-known NIR phosphors. Additionally, the NIR camera can capture the image of license plate and nectarine, as well as identify the residual drug content in the bottle under the irradiation of the NIR device constructed by the glass-ceramics. This work not only presented an ultra-broadband and high-efficiency NIR material but also highlights a design strategy to effectively enhance the efficiency and broadband characteristics of NIR glass-ceramics.

Ultra-broadband near-infrared Cr3+-doped multi-phase glass-ceramics realized by the selective enrichment strategy for near-infrared spectroscopy applications

As a very important component of NIR spectroscopy, the enhancement of luminescent efficiency and the broadening of bandwidth for NIR light sources are still considered to be a challenge. Hereon, a novel Cr3+-doped MgO-Al2O3-SiO2 multi-phase glass-ceramics was successfully constructed. Upon excitation of 400 nm, the glass-ceramics presented an ultra-broadband NIR emission peaking at ∼910 nm with full width at half maximum of >270 nm, and the internal/external quantum efficiency of 60.4 %/28.8 %. The integrated emission intensity remained at ∼86.6 %/80.9 % at 100 ℃/150 ℃ compared to the intensity at room temperature. Furthermore, a NIR device was made by encapsulating the glass-ceramics on 405 nm LED, which presented a NIR output power and photoelectric conversion efficiency of 322 mW/1117 mW and 2.72 %/2.39 % at the driven current of 100 mA/320 mA, respectively. This work realized simultaneous adjustment of luminescent efficiency and bandwidth by selective enrichment of Cr3+ ions into different crystal phases, which provides an effective strategy for improving the luminescent efficiency and bandwidth of NIR glass-ceramics.

Luminescence characteristics of ultra-broadband near-infrared emission Li3Mg2SbO6:Cr3+ phosphors and their applications in light-emitting diodes

In this study, a Li3Mg2SbO6:Cr3+ phosphor was prepared by high-temperature solid-phase reaction. The phosphors doped with 0.03Cr3+ showed broadband emission at 805 nm, a wide spectral band of 200 nm at 435 nm excitation, an internal quantum efficiency of 80.8%, and the integrated emission intensity at 423 K of Li3Mg2SbO6:Cr3+ is about 50% of that at room temperature. The phosphors conversion (pc) - light-emitting diodes (LEDs) with broadband near-infrared (NIR) emission were prepared using the Li3Mg2SbO6:Cr3+ phosphor coating on blue LED chips. They achieved 10.4% photoelectric efficiency and 60.2 mW NIR output power at 210 mA. All results showed that the Li3Mg2SbO6:Cr3+ phosphors had considerable potential in NIR spectroscopy applications.

Y2MAl4SiO12:Cr3+ (M=Mg, Ca, Sr, Ba) near-infrared phosphors via chemical unit co-substitution strategy for plant growth

Near infrared light plays an important role in promoting the growth and development of plants. Light at 600–800 nm is conducive to the growth and development of plant stems and leaves. In this study, a series of near-infrared phosphors Y2MAl4SiO12:Cr3+ (M = Mg, Ca, Sr, Ba) were synthesized by high temperature solid phase method. The local environment of Cr3+ in Y3Al5O12(YAG) structure was regulated by different Mg2+/Ca2+/Sr2+/Ba2+-Si4+ co-substituting Y3+-Al3+. The crystal structures of the phosphors were analyzed by X-ray diffraction (XRD) and Rietveld refinement. With the entry of Mg2+→Ba2+ into the matrix lattice, the corresponding luminescence intensity of Mg2+→Ba2+ is enhanced, the spectra show a large degree of redshift of about 50 nm and the spectra of Mg2+→Ba2+ samples widen by 12 nm. The results show Y2BaAl4SiO12: Cr3+ has a better luminescence property and 0.03 mol is an optimized content. The internal quantum efficiency (IQY) is 68.02% and integrated emission intensity at 150 °C remains 40.2% of the initial emission intensity. The calculated activation energy ΔE is 1.58eV. The spectra of Y2BaAl4SiO12:0.03Cr3+ phosphors are well matched with the absorption spectra of PR and PFR, which is expected to have potential applications in plant growth.

Cr3+-activated NaInSi2O6: An efficient broadband near-infrared phosphor with its applications in LED

A novel near-infrared (NIR) emitting Cr3+-doped clinopyroxene NaInSi2O6 phosphor is designed and synthesized by solid-state method. There are three absorption bands in the NaInSi2O6: 0.04Cr3+ phosphor, peaking at ∼300 nm, ∼470 nm and ∼690 nm, respectively. A broad emission band ranging from 700 nm to 1300 nm is detected at 466 nm excitation, peaking at 936 nm with a full width at half maximum (FWHM) of 151 nm. At the same time, the calculated weak crystal field strength of Cr3+ is 1.93 in the NaInSi2O6 host, resulting in its characteristic broadband emission. Furthermore, the internal quantum efficiency (IQE) and external quantum efficiency (EQE) of NaInSi2O6: 0.04Cr3+ are 68.9% and 27.4%. The integrated emission intensity of NaInSi2O6: 0.04Cr3+ at 423 K retains 55.2% of that at 293 K. By contrast, the NaInSi2O6: 0.04Cr3+-based phosphor-in-glass (PiG) exhibits better thermal stability (64.9%@423 K). A NIR phosphor-converted light emitting diode (pc-LED) was manufactured using a InGaN chip and NaInSi2O6: 0.04Cr3+, presenting the NIR output power of 30.47 mW@200 mA. Used as a NIR light source, the prepared pc-LED shows good promise in the fields of biological tissue imaging and night vision.