Efficient Ultra‐Broadband Ga4GeO8:Cr3+ Phosphors with Tunable Peak Wavelengths from 835 to 980 nm for NIR pc‐LED Application

• Published in: Advanced optical materials 2022-02, Vol.10 (4), p.n/a
• Main Authors: Yao, Leqi, Shao, Qiyue, Shi, Meiling, Shang, Tianqi, Dong, Yan, Liang, Chao, He, Jinhua, Jiang, Jianqing
• Format: Article
• Language: English
• Subjects: Broadband; Cr 3+doping; Light emitting diodes; Materials science; Near infrared radiation; near‐infrared emission; Night vision; Optics; Phosphors; Trivalent chromium; tunable broadband emission
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.202102229

Near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) hold great potential for applications ranging from night vision to non‐destructive detection. However, it remains a long‐standing challenge to develop NIR phosphors simultaneously with longer‐wavelength broadband emissions and higher efficiency. Herein, ultra‐broadband Ga4GeO8:Cr3+ (GGO:Cr3+) phosphors are developed, with the NIR emission covering 700–1300 nm. Furthermore, tunable emission bands peaking from 835 to 980 nm are achieved simply by varying the Cr3+ concentration. Particularly, emission maxima (λmax) of GGO:xCr3+ shift from 850 to 900 nm without intensity loss when increasing x values between 0.02 and 0.10. An internal quantum yield of 60% is achieved for GGO:0.02Cr3+ (λmax ≈ 850 nm, full width at half maximum (FWHM) ≈215 nm). The origin of tunable ultra‐broadband emissions of GGO:Cr3+ is revealed on the basis of structural and time‐resolved spectroscopic analysis. The pc‐LED fabricated by GGO:0.02Cr3+ exhibits a maximum NIR output power of ≈56 mW at 400 mA drive current, and its application in high‐penetration quality analysis of fruits is also demonstrated. The results indicate that GGO:Cr3+ phosphors have high promise for practical applications in NIR pc‐LED devices. Novel Ga4GeO8:Cr3+ near‐infrared (NIR) phosphors with multiple Cr3+ centers are developed showing efficient ultra‐broadband emissions in the 700–1300 nm range. Meanwhile, tunable emissions peaking from 835 to 980 nm are achieved by increasing the Cr3+ concentration. High‐penetration spectroscopic analysis on inner quality of fruits is also demonstrated using the fabricated high‐power NIR phosphor‐converted light‐emitting diodes (pc‐LEDs).