Near‐Infrared Light‐Emitting Diodes utilizing a Europium‐Activated Calcium Oxide Phosphor with External Quantum Efficiency of up to 54.7%

Advanced Materials, Journal Year: 2022, Volume and Issue: 34(26)

Published: April 15, 2022

Near-infrared (NIR) luminescence materials with broadband emissions are necessary for the development of light-emitting diodes (LEDs) based light sources. However, most known NIR-emitting limited by their low external quantum efficiency. This work demonstrates how photoluminescence efficiency europium-activated calcium oxide (CaO:Eu) NIR phosphor can be significantly improved and stabilized at operating temperatures LEDs. A carbon paper wrapping technology is innovatively developed used during solid-state sintering to promote reduction Eu3+ into Eu2+ . In parallel, oxygen vacancies in CaO lattice repaired utilizing GeO2 decomposition. Through this process, a record-high 54.7% 740 nm obtained thermal stability greatly from 57% 90% 125 °C. The as-fabricated NIR-LEDs reach record photoelectric (100 [email protected]%) output power mA @ 319.5 mW). discovery high-performance phosphors will open new research avenues LED sources variety photonics applications.

Language: Английский

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Recent Advances in Chromium‐Doped Near‐Infrared Luminescent Materials: Fundamentals, Optimization Strategies, and Applications

Advanced Optical Materials, Journal Year: 2022, Volume and Issue: 11(3)

Published: Dec. 5, 2022

Abstract Development of chromium‐doped luminescent materials is pertinent to many emerging applications, ranging from agriculture, food industry noninvasive health monitoring. The fundamental importance chromium‐activated in the field optics and biomedicine makes rapid development novel relevant applications. Herein, recent advances on luminescence principle photoluminescence (PL) optimization for Cr 3+ ‐activated together with their potential applications are reviewed. different types most recently developed ‐doped design principles systematically summarized. associations between crystal structure near‐infrared (NIR) PL properties, as well performance‐evaluating parameters introduced examples known NIR emitting phosphors, which will be helpful explore future materials. Based control, site engineering, electron–phonon coupling, several efficient strategies optimizing performances including bandwidth, thermal stability, quantum efficiency proposed. Then, fields analysis, night vision, information encryption, optical sensors surveyed. Finally, challenges promising

Language: Английский

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Efficient and Thermally Stable Broad-Band Near-Infrared Emission in a KAlP₂O₇:Cr³⁺ Phosphor for Nondestructive Examination

ACS Applied Materials & Interfaces, Journal Year: 2022, Volume and Issue: 14(9), P. 11663 - 11671

Published: Feb. 23, 2022

Broad-band near-infrared (NIR) phosphors are essential to assembling portable NIR light sources for applications in spectroscopy technology. However, developing inexpensive, efficient, and thermally stable broad-band remains a significant challenge. In this work, phosphate, KAlP2O7, with wide band gap suitable electronic environment Cr3+ equivalent substitution was selected as the host material. The synthesized KAlP2O7:Cr3+ material exhibits emission covering 650-1100 nm peak centered at 790 full width half-maximum (fwhm) of 120 under 450 excitation. internal quantum efficiency (IQE) determined be 78.9%, intensity 423 K still maintains 77% that room temperature, implying high excellent thermal stability Finally, phosphor-converted light-emitting diode (pc-LED) device fabricated by using as-prepared combined blue LED chip, which presents output power 32.1 mW photoelectric conversion 11.4% drive current 100 mA. Thus, work not only provides an inexpensive performance pc-LEDs but also highlights some strategies explore class materials.

Language: Английский

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Modulation of Thermally Stable Photoluminescence in Cr³⁺-Based Near-Infrared Phosphors

The Journal of Physical Chemistry Letters, Journal Year: 2022, Volume and Issue: 13(22), P. 5001 - 5008

Published: June 1, 2022

Broadband near-infrared (NIR) light sources based on phosphor-converted light-emitting diodes (pc-LEDs) are desirable for various photonics applications, while developing thermally stable NIR phosphors remains a great challenge. Increasing the temperature accelerates severe nonradiative relaxation process gorverned by intrinsic energy gap law, which further suspends efficient low-energy emission of Cr3+ emitters in inorganic lattice. To address this rule, several state-of-the-art strategies have been put forward perspective to modulate critical law from viewpoints (1) crystal structure design, (2) defect engineering, (3) strengthened rigidity, and (4) transfer. This suggests avenues exploring novel broadband with high thermal stability will also stimulate studies spectroscopy high-power applications.

Language: Английский

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Photoluminescence Properties of AScSi₂O₆:Cr³⁺ (A = Na and Li) Phosphors with High Efficiency and Thermal Stability for Near-Infrared Phosphor-Converted Light-Emitting Diode Light Sources

ACS Applied Materials & Interfaces, Journal Year: 2022, Volume and Issue: 14(6), P. 8179 - 8190

Published: Feb. 3, 2022

Near-infrared (NIR) phosphors are fascinating photoluminescence materials with applications in phosphor-converted light-emitting diodes (pc-LEDs) for night vision lighting, which still restricted by low efficiency and thermal stability the current research stage. In this work, AScSi2O6 (A = Na/Li) chosen as hosts due to a larger band gap single octahedral site Cr3+ doping. The NIR-emitting Cr3+-activated AScSi2O6:Cr3+ were successfully prepared common high-temperature solid-state method. X-ray diffraction Rietveld refinement confirm that prefers enter Sc3+-octahedral lattice structure. Under blue light excitation, exhibit broadband NIR emission from 700 1100 nm full width at half-maximum of ∼150 owing 4T2 → 4A2 electron transition Cr3+. properties enhanced adjusting fluxes sintering conditions, highly efficient LiScSi2O6:Cr3+ external quantum efficiencies 33.4% obtained. Moreover, optimized exhibits excellent (75% 150 °C) an activation energy 0.33 eV. Importantly, fabricated pc-LED phosphor demonstrates brighter higher luminous efficacy than NaScSi2O6:Cr3+ vision.

Language: Английский

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Achieving High Quantum Efficiency Broadband NIR Mg₄Ta₂O₉:Cr³⁺ Phosphor Through Lithium‐Ion Compensation

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(22)

Published: March 3, 2023

Ultra-efficient broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) are urgently needed to improve the detection sensitivity and spatial resolution of current smart NIR spectroscopy-based techniques. Nonetheless, performance pc-LED has severely limited owing external quantum efficiency (EQE) bottleneck materials. Herein, a blue LED excitable Cr3+ -doped tetramagnesium ditantalate (Mg4 Ta2 O9 , MT) phosphor is advantageously modified through lithium ion as key efficient emitter achieve high optical output power light source. The emission spectrum encompasses 700-1300 nm electromagnetic first biological window (λmax = 842 nm) with full-width at half-maximum (FWHM) ≈2280 cm-1 (≈167 nm), achieves record EQE 61.25% detected 450 excitation Li-ion compensation. A prototype fabricated MT:Cr3+ Li+ evaluate its potential practical application, which reveals an 53.22 mW driving 100 mA, photoelectric conversion 25.09% 10 mA. This work provides ultra-efficient luminescent material, shows great promise in applications presents novel option for next-generation high-power compact sources.

Language: Английский

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Broadband NIR Phosphor Ca₂LuScAl₂Si₂O₁₂:Cr³⁺ for NIR LED Applications

Advanced Optical Materials, Journal Year: 2022, Volume and Issue: 10(24)

Published: Oct. 26, 2022

Abstract Near‐infrared phosphor‐converted light‐emitting diodes (NIR pc‐LEDs) have promising applications in food analysis, night vision imaging, and biological probes. Developing NIR phosphors with broadband emission high efficiency has attracted immense interest. Herein, a novel phosphor Ca 2 LuScAl Si O 12 :Cr 3+ (CLSAS:Cr ) is reported for the first time. Under excitation of 442 nm light, CLSAS:Cr shows from 600 to 900 full width at half maximum (FWHM) 142 nm, benefiting emissions two Cr centers CLSAS, which proved by spectra decay curves. The internal quantum (IQE) 73.7% achieved and, 423 K, intensity maintains 76% value room temperature. Combining 450 blue chip, pc‐LED fabricated demonstrated fast imaging veins human palm fist, as well objects.

Language: Английский

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Thermally Stable Red‐Emitting Oxide Ceramics for Laser Lighting

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(30)

Published: April 22, 2023

Laser-driven phosphor-converted white light sources are highly desirable for their unprecedented energy efficiency and lighting quality. However, important challenges remain due to a lack of efficient stable red-emitting materials. Here Eu2+ -activated oxide-based double perovskites explored as red emitters with thermally photoluminescence. Sr3 TaO5.5 :Eu2+ ceramics exhibit emission band peaking at 620 nm upon blue laser pumping owing the occupation ordered substitutional lattice sites. A constructed laser-driven wheel under an incident power density 19.2 W mm-2 presents record luminous flux 1115 lm excellent color rendering index 90. This study invigorates development luminescence laser-pumped display applications.

Language: Английский

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Recent progress in Ce³⁺/Eu²⁺-activated LEDs and persistent phosphors: focusing on the local structure and the electronic structure

Journal of Materials Chemistry C, Journal Year: 2022, Volume and Issue: 11(1), P. 48 - 96

Published: Nov. 2, 2022

The theoretical and experimental progress in the Ce 3+ /Eu 2+ activated LEDs persistent phosphors is reviewed. We expound an overall vision on composition–structure–property correlations development routines of some typical phosphors.

Language: Английский

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Valence conversion and site reconstruction in near-infrared-emitting chromium-activated garnet for simultaneous enhancement of quantum efficiency and thermal stability

Light Science & Applications, Journal Year: 2023, Volume and Issue: 12(1)

Published: Oct. 7, 2023

Achievement of high photoluminescence quantum efficiency and thermal stability is challenging for near-infrared (NIR)-emitting phosphors. Here, we designed a "kill two birds with one stone" strategy to simultaneously improve the NIR-emitting Ca3Y2-2x(ZnZr)xGe3O12:Cr garnet system by chemical unit cosubstitution, revealed universal structure-property relationship luminescence optimization mechanism. The cosubstitution [Zn2+-Zr4+] [Y3+-Y3+] played critical role as reductant promote valence transformation from Cr4+ Cr3+, resulting reconstruction octahedral sites Cr3+. introduction also contributed rigid crystal structure. These aspects together realized internal 96% excellent 89%@423 K. Moreover, information encryption "burning after reading" was achieved based on different resistance phosphors acid. developed phosphor-converted light-emitting diode demonstrated promising applications in bio-tissue imaging night vision. This work provides new perspective developing high-performance phosphor materials.

Language: Английский

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