Simultaneously enhanced far-red luminescence and thermal stability in Ca3Al4ZnO10:Mn4+ phosphor via Mg2+ doping for plant growth lighting

摘要： Non-rare-earth-based Ca3Al4ZnO10:Mn4+,Mg2+ (CAZO:Mn4+,Mg2+) phosphors with admirable luminescence performance and great potential as far-red light source for plant growth light-emitting diodes (LEDs) were reported in this paper. The concentration-dependent optical properties of the as-prepared phosphors were investigated in detail. Under ultraviolet-light excitation at 358 nm, the composition-optimized CAZO:0.4%Mn4+,14%Mg2+ phosphor showed an intense broad far-red emission band in the 625-830 nm wavelength range with a maximum at 714 nm, which was due to the 2Eg→4A2g transition of Mn4+ ions. The luminescence intensity of the CAZO:0.4%Mn4+,14%Mg2+ phosphor was about 1.82 times higher than that of CAZO:0.4%Mn4+ phosphor, and the corresponding mechanism for the luminescence enhancement via Mg2+ doping was studied. Amazingly, the internal quantum efficiency of the CAZO:0.4%Mn4+ phosphor was increased from 31 to 60% after co-doping 14 mol% Mg2+. The CAZO:0.4%Mn4+,14%Mg2+ phosphor also showed enhanced thermal stability compared with the CAZO:0.4%Mn4+ counterpart. It was found that, for CAZO:0.4%Mn4+,14%Mg2+ phosphor, the emission intensity at 423 K (150 oC) was about 51% of that at 303 K (30 oC), while the corresponding activation energy was determined to be 0.245 eV.