Key Takeaways & Executive Findings
- •• • LBASO:0.07Cr3+ achieves IQE of 84.82% and EQE of 46.02%, enabling high-efficiency NIR pc-LEDs with reduced energy loss for solid-state lighting. • • Anti-thermal quenching of 126.03% at 498 K under 442 nm excitation ensures stable emission at elevated temperatures, critical for high-power LED operation. • • NIR pc-LED delivers 134.99 mW output power and 11.4% photoelectric conversion efficiency at 100 mA, demonstrating practical viability for industrial applications. • • Chemical unit cosubstitution [Ba2+-Si4+] for [Lu3+-Al3+] in LuAG garnet induces strong crystal field, shifting emission to 705 nm, enabling spectral tuning for specific applications.
Abstract
Near-infrared (NIR) phosphors with high quantum efficiency (QE) and thermal robustness are critical for phosphor-converted light-emitting diodes (pc-LEDs). Here, a Cr3+-activated Lu2BaAl4SiO12 (LBASO) garnet phosphor is engineered via chemical unit cosubstitution of [Ba2+-Si4+] for [Lu3+-Al3+] in Lu3Al5O12 (LuAG), inducing a strong crystal field that yields NIR emission at 705 nm. The optimized LBASO:0.07Cr3+ exhibits an internal quantum efficiency (IQE) of 84.82% and external quantum efficiency (EQE) of 46.02%. Notably, it demonstrates anti-thermal quenching (ATQ) with 126.03% of its initial intensity at 498 K under 442 nm excitation, attributed to a wide band gap, weak electron-phonon coupling, defect trap energy levels, high structural rigidity, and optimized electron population distribution. A NIR pc-LED fabricated with this phosphor achieves an output power of 134.99 mW and photoelectric conversion efficiency of 11.4% at 100 mA drive current. These results underscore the potential of LBASO:Cr3+ for applications in plant lighting, night vision, and nondestructive analysis.
1. Introduction
Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) are pivotal for applications in plant growth monitoring, night vision, and non-destructive analysis. However, conventional NIR phosphors suffer from low quantum efficiency and severe thermal quenching, which degrade performance under high-power operation. The bottleneck lies in achieving both high emission efficiency and thermal stability simultaneously, as phonon-assisted non-radiative transitions typically increase with temperature, reducing luminescence.
This work addresses this challenge by engineering the garnet host lattice through chemical unit cosubstitution, replacing [Lu3+-Al3+] with [Ba2+-Si4+] in Lu3Al5O12. This substitution strengthens the crystal field around Cr3+ activators, promoting sharp-line emission at 705 nm. The resulting LBASO:Cr3+ phosphor exhibits exceptional internal quantum efficiency (84.82%) and anti-thermal quenching (126.03% at 498 K), attributed to a wide band gap, weak electron-phonon coupling, and defect engineering. These properties directly overcome the efficiency-thermal stability trade-off, enabling high-performance NIR pc-LEDs for multifunctional optoelectronics.
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Fangrui Cheng, Yixuan Lai, Yifei Zhao, Runying Zheng, Chengjie Li, Luxia Zhong, Fangmin Lin, Yizhi Zheng, Ruirui Yang, Renping Cao, Yinghan Wang, Hang Zhu, Shi Ye, Xiping Jing (2026). Defect and Crystal Field Engineering Enables High Efficiency and Anti-Thermal Quenching in Cr3+ Doped Rigid Garnet Phosphors for Multifunctional Optoelectronics. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3790-5
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Frequently Asked Questions
What is the mechanism behind the anti-thermal quenching observed in LBASO:Cr3+ at 498 K?
The anti-thermal quenching (126.03% at 498 K) is primarily attributed to the wide band gap of the host, which suppresses thermal ionization, and weak electron-phonon coupling that reduces non-radiative transitions. Additionally, defect trap energy levels capture electrons at elevated temperatures, delaying thermal quenching, while the rigid garnet structure maintains high structural integrity.
How does the chemical unit cosubstitution of [Ba2+-Si4+] for [Lu3+-Al3+] affect the crystal field and emission wavelength?
The cosubstitution alters the local coordination environment around Cr3+ ions, increasing the crystal field strength (Dq/B). This shifts the emission from broadband (4T2→4A2) to sharp-line (2E→4A2) at 705 nm, as evidenced by the strong crystal field NIR emission characteristics.
What are the potential scalability challenges for industrial production of LBASO:Cr3+ phosphors?
Scalability may be challenged by the high synthesis temperatures required for garnet formation and the precise control of Cr3+ concentration (0.07) to avoid concentration quenching. However, the use of conventional solid-state reaction methods and abundant raw materials (Lu, Ba, Al, Si) suggests cost-effective production is feasible.
How does the performance of LBASO:Cr3+ compare to commercial NIR phosphors in terms of quantum efficiency and thermal stability?
LBASO:Cr3+ achieves an IQE of 84.82% and EQE of 46.02%, which is competitive with or superior to many commercial NIR phosphors. Its anti-thermal quenching (126.03% at 498 K) is exceptional, as most phosphors exhibit intensity loss at such temperatures, making it suitable for high-power LED applications.
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