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Abstract Even though there have been significant advancements in the development of Cr 3+ ‐activated near‐infrared (NIR) phosphors, the challenge still remains to develop highly efficient and thermally stable NIR phosphors. Here, the Ca 4‐x Zn x HfGe 3 O 12 :0.03Cr 3+ solid solution phosphors with 834–806 nm NIR emission are constructed by substituting Zn 2+ for Ca 2+ , thereby facilitating the formation of ZnO 6 luminescence site. The coexistence of HfO 6 and Zn/CaO 6 luminescence centers is confirmed through DFT calculation, time‐resolved photoluminescence (TRPL) spectroscopy, and low‐temperature‐photoluminescence (77 K) spectroscopy. The formation of ZnO 6 effectively resolves the issue of lattice mismatch between Cr 3+ and Ca 2+ . Furthermore, the simultaneous enhancement of luminescence intensity and thermal stability is realized through a synergistic combination of lattice distortion and rigidity enhancement. By optimizing the substitution concentration of Cr 3+ , the internal quantum efficiency (IQE) of 92% and an external quantum efficiency (EQE) of 29% are finally achieved. Meanwhile, the thermal stability is also enhanced from 59%@400 K (x = 0) to 81%@400 K (x = 0.8). The developed NIR phosphor‐converted light‐emitting diodes (pc‐LEDs) exhibit promising prospects in the fields of security, biomedicine, non‐destructive testing and rapid identification.
Wang et al. (Fri,) studied this question.