Efficient Ultra‐Broadband Ga ₄ GeO ₈ :Cr ³⁺ Phosphors with Tunable Peak Wavelengths from 835 to 980 nm for NIR pc‐LED Application

Abstract 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 Ga ₄ GeO ₈ :Cr ³⁺ (GGO:Cr ³⁺ ) 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 Cr ³⁺ concentration. Particularly, emission maxima (λ _max ) of GGO: x Cr ³⁺ 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:0.02Cr ³⁺ (λ _max ≈ 850 nm, full width at half maximum (FWHM) ≈215 nm). The origin of tunable ultra‐broadband emissions of GGO:Cr ³⁺ is revealed on the basis of structural and time‐resolved spectroscopic analysis. The pc‐LED fabricated by GGO:0.02Cr ³⁺ 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:Cr ³⁺ phosphors have high promise for practical applications in NIR pc‐LED devices.