Persistent luminescence (PersL) materials have emerged as an outstanding optical media with versatile applications in data storage, anti-counterfeiting, and beyond. However, their practical implementation is critically hindered by insufficient PersL intensity, a challenge fundamentally rooted in the incomplete understanding of trapping mechanisms. Here, we developed Tb 3+ -activated Ga 4 GeO 8 phosphors with rational defect manipulation via Ln 3+ (Ln = Pr, Eu, Ce, Er) co-doping strategies. Especially, when Eu 3+ /Er 3+ are introduced as lattice distortion agents into Tb 3+ -doped Ga 4 GeO 8 , the phosphors demonstrate dual-band PersL including blue-green PersL from Tb 3+ 5 D 4 → 7 F J transitions (492–620 nm) and red-NIR PersL emission (715 nm) originating from oxygen defect levels. Through systematic exploration of the PersL mechanism, we propose a criterion for effective trapping: stabilizing V O •• defect energy levels by replacing matrix cations with less electronegative species (e.g., Eu 3+ , Er 3+ ), which suppresses non-radiative V O defect states. This study establishes design guidelines for the rational development of high-performance PersL materials.
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.
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