Compact and portable near-infrared (NIR) light sources have been widely used in the fields of NIR spectroscopy, night vision lighting, medical measurement, etc. Although Cr 3+ -activated phosphors have been widely reported, achieving broadband and high-efficiency near-infrared emission remains of great significance. In this work, CaZnGe 2 O 6 :Cr 3+ with highly efficient and ultrabroadband NIR emission was synthesized by a solid reaction method, and Yb 3+ -codoping not only enhanced the NIR emission efficiency but also broadened its emission band. As the absorption efficiency was greatly improved due to Yb 3+ doping, CaZnGe 2 O 6 :Cr 3+ ,Yb 3+ presented excellent NIR emission properties with a fwhm of 295 nm, an internal quantum efficiency (IQE) of 98.4, an external quantum efficiency (EQE) of 31.1%, and an effective emission band for NIR spectroscopy over 350 nm. A pc-LED was prepared by packaging the CaZn-Ge 2 O6:Cr 3+ ,Yb 3+ phosphor with a 460 nm LED chip, and its NIR electro-optical conversion efficiency and output power reached 12.9%@100 mA and 249.3 mW@300 mA, respectively. This pc-LED can illuminate a pattern clearly on wall 15 m away and demonstrated application in NIR spectroscopy through the measurement of the glucose solution concentration. Our results indicate that the CaZnGe 2 O 6 :Cr 3+ ,Yb 3+ ultrabroadband NIR phosphor is a high-performance light source material for portable compact NIR devices.

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Metal halides (MHs) show great potential in photovoltaic and optoelectronic applications, but their lack of long-term stability limits their applications for their sensitivity to oxygen, moisture, strong light irradiation, and high temperature. In this report, lead-free MHs CsCu2I3/Cs3Cu2I5 dual-phase glass-ceramics were prepared with a traditional melting-quenching method by using solid reductive agent Si3N4. Ultrabroadband emission from violet to near-infrared (350–800 nm) can be obtained from these CsCu2I3/Cs3Cu2I5 dual-phase glass-ceramics with long-term water-resistance stability. Detailed analysis of microstructure, spectra, and calculation reveals that the ultrabroadband nature can be ascribed to the intense emission of CsCu2I3 NCs, Cu+ ions, and Cs3Cu2I5 NCs together, and especially, the emission from Cs3Cu2I5 NCs and Cu+ ions presents a cyan color. Our work not only demonstrates that CsCu2I3/Cs3Cu2I5 glass-ceramic is a promising fluorescent material, but also develops a method to prepare lead-free metal halides CsCu2I3/Cs3Cu2I5 dual-phase glass-ceramics with high stability, paving the way for their applications.

It remains a challenge to induce robust long-range ferromagnetism in graphene. Doping nitrogen in high concentration is considered as a potential approach. In this paper, three new graphitic carbon nitride structures with energetic stability in chemical formulae of C10N6, C9N7 and C7N9 are proposed and investigated by first-principles calculation. Both C10N6 and C9N7 are half-metals, and C7N9 is a spin-polarized metal. The itinerant p electrons occupy the spin-polarized narrow bands near the Fermi level, which induces Stoner ferromagnetism in the C10N6 and C9N7. The direct exchange between the delocalized magnetic moment of the itinerant π electrons is responsible for the ferromagnetism in the C7N9. The magnetic moment is determined by both spin-polarized electronic structures and long-range magnetic interaction. Intriguingly, besides the magnetic interactions between the itinerant π electrons, we also find direct magnetic interaction between localized in-plane unpaired electrons. Our results will assist in understanding ferromagnetism and motivate new experiments to produce robust magnetism in graphene-like materials following the proposed synthesis strategy.