High‐Performance NIR Emission in Chromium‐Doped Garnet Phosphors Enabled by Structure and Excitation Regulation

• Published in: Laser & photonics reviews 2024-01, Vol.18 (1), p.n/a
• Main Authors: Li, Zhuowei, Zhu, Ge, Li, Shanshan, Xu, Wen, Bian, Qingfeng, Cong, Yan, He, Ming, Luo, Xixian, Xin, Shuangyu, Dong, Bin
• Format: Article
• Language: English
• Subjects: broadband emission; Cr3; Excitation; garnet; Garnets; Light emitting diodes; Luminescence; Luminous intensity; Near infrared radiation; Night vision; pc‐NIR LEDs; Phosphors; Photoelectricity; Quantum efficiency; Solid solutions; Thermal stability
• ISSN: 1863-8880; 1863-8899
• DOI: 10.1002/lpor.202300732

The burgeoning phosphor‐converted near‐infrared light‐emitting diodes (pc‐NIR LEDs) have important applications in special illumination and spectroscopy analysis. However, the development of efficient NIR‐emitting phosphors with high performance is still a challenge. In this work, a chemical unit co‐substitution strategy is proposed to realize the excitation transition regulation and successfully achieve high‐performance NIR luminescence in Ca3‐yNayMg1‐ySb2‐xAl2+yO12: xCr3+ (0 ≤ x ≤ 0.05, 0 ≤ y ≤ 1) garnet‐type solid solution phosphors. Through the excitation transition modulation from the 4A2 ground state to the 4T1(4P) and 4T1(4F) excitation state, the excitation intensity at the blue light region is largely enhanced by 25.6 times. Moreover, the NIR‐emitting efficiency and thermal stability are improved, with the optimal luminescence internal quantum efficiency of 90.6% and thermal stability of 97%@423 K, without any flux‐assisted sintering or reduction atmosphere protection. The structure regulation induced small Stokes shift, weak electron‐phonon coupling effect, and decreased non‐radiative transition are responsible for the excellent NIR‐emitting performance. Finally, the NIR pc‐LED is fabricated with photoelectric efficiencies of 18.7%@100 mA and NIR output powers of 63 mW@100 mA, presenting potential applications in nondestructive internal defect detection, veins imaging, and night vision surveillance. A chemical unit co‐substitution strategy is proposed to realize the excitation regulation and achieve high‐performance near‐infrared (NIR)‐emission in Ca3‐yNayMg1‐ySb2‐xAl2+yO12:xCr3+ phosphors. The structure and spectroscopy regulation process, NIR luminescence behavior, and related crystal field strength parameters are investigated. Finally, the NIR phosphor‐converted light‐emitting diode is fabricated, and the potential applications toward nondestructive detection, veins imaging, and night vision surveillance are demonstrated.