| Lanthanide(Ln3+)and transition metal ions coactivate near-infrared(NIR)luminescent materials have been widely applied in the fields of spectral converters for solar cell,solid-state lasers,bioimaging,Ge photovoltaic devices,optical amplifiers for telecommunication and biological fluorescent probes owing to their unique and superior near-infrared luminescent properties.However,Ln3+ coactivate phosphors usually exhibits weak and narrow line-like absorption in the visible and near infrared(NIR)spectral ranges owing to the 4f-4f forbidden transitions.This results in its low excitation efficiency and correspondingly the weak NIR emission.Sensitization is an important approach to increase NIR emission via enhancing the absorption efficiency of Ln3+.In this paper,double perovskite Y2MgTiO6 phosphors coactivate with different trivalent rare-earth(RE)ions(Tm3+,Nd3+,Ho3+)and tetravalent manganese ions were synthesized by high temperature solid phase method.Utilize Mn4+ ion effective energy transfer to rare earth ions(Tm3+,Nd3+,Ho3+),thereby realizing characteristic emission of rare earth ions(Tm3+,Nd3+,Ho3+)or Mn4+ ions,and then applied to near-infrared solar cells,solid-state lasers,bioimaging,Ge photovoltaic devices,optical amplifiers for telecommunication and biological fluorescent probes.In addition,the energy transfer mechanism in the Mn4+/RE3+ coactivate Y2MgTiO6 single-matrix material was revealed by the study of spectral properties and fluorescence dynamics.Mn4+/Tm3+ coactivate Y2MgTiO6 near-infrared fluorescent materials were prepared by high temperature solid phase reaction,the mutual energy transfer process between Mn4+ and Tm3+ under different excitation was observed.The NIR emission(800 nm 3H4?3H6)arises from resonant energy transfer from Mn4+ to Tm3+ and downshift of Tm3+.The two NIR emissions(1488 nm,3H4?3F4;1800 nm,3F4?3H6)arise from resonant energy transfer from Mn4+ to Tm3+ and downconversion of Tm3+ in the process of energy transfer from Mn4+ to Tm3+.Based on Dexter's theory,the energy transfer mechanism is mainly contributed to a dipole-dipole interaction between Mn4+ and Tm3+ ions,which is responsible for the largely enhanced multiwavelength near infrared emission of Tm3+.Multiwavelength near infrared emissions of Tm3+ make Y2MgTiO6:Mn4+/Tm3+ phosphors potential application in solid state lasers,bioimaging,Ge photovoltaic devices(band gap approximately 0.67 eV)and so on.A series of different manganese ion and Ho3+ ion doping concentrations Mn4+/Nd3+coactivate Y2MgTiO6 near infrared fluorescent materials were prepared by high temperature solid phase reaction.NIR emission of Nd3+ ions sensitized by Mn4+ at 331 nm was observed at 885 nm and 1085 nm.The mutual energy transfer mechanism between Mn4+ and Nd3+ ions was studied in detail.The results show that the resonance energy transfer and phonon auxiliary energy transfer from Mn4+ to Nd3+.Manganese ion sensitized Nd3+ 1085 nm near infrared luminescence enhanced it by 5 times.Nd3+ multi-wavelength near-infrared emission makes YMT:Mn4+/Nd3+ phosphors have potential application value in the fluorescence conversion layer of monocrystalline silicon solar cells.YMT:Mn4+/Ho3+ near infrared fluorescent materials were prepared by high temperature solid phase method.The energy transfer from manganese ions to Ho3+ ions is mainly realized through the resonance energy transfer and phonon-assisted energy transfer process to achieve the single-band near-infrared luminescence of Ho3+ ions.Single-band near infrared emission at 1197 nm was observed in the Mn4+/Ho3+ co-doped yttrium titanate YMT system.Manganese ion sensitized Ho3+ 1197 nm single-band near-infrared emission enhanced its luminescence intensity by 18 times.The emission wavelength of 1197 nm is located in the second optical window of biology,which makes Ho3+ doped near-infrared luminescence materials have a broad application prospect in biological imaging,fluorescence labeling and other fields. |
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