Near Infrared Luminescence Of Tm³⁺(Yb³⁺) Sensitized By Mn⁴⁺

The near infrared luminescence has a particularly wide range of applications in human eye safety lasers,remote sensing measurements,solar cells and biofluorescence imaging.Rare earth elements have special 4f electron shell structure and rich energy level,and as an activator doping can emit a variety of near-infrared band of light.Therefore,based on rare earth ion doping near-infrared luminescent materials have attracted the attention of researchers.As the existing Tm³⁺ and Yb³⁺ion doping near-infrared luminescent materials mostly show the absorption intensity is weak,the luminous intensity is not strong enough and other issues,resulting in its practical application is limited.Therefore,the near-infrared luminescence intensity of Tm³⁺ and Yb³⁺ ions is improved by searching for suitable sensitizers and matrices.Specific work content:In chapter 3,we mainly studied the Mn⁴⁺/Tm³⁺ co-doped Ca₁₄Zn₆Al₁₀O₃₅near-infrared phosphor which was prepared by sol-gel method.The Mn⁴⁺ has a strong excitation efficiency in Ca₁₄Zn₆Al₁₀O₃₅ matrix,and has strong absorption in the range of ultraviolet light and visible light.At 455 nm light excitation,it is found that at the optimum Tm³⁺ and Mn⁴⁺ ion doping concentration,the Tm³⁺:1.85 m m near-infrared light intensity is about 24 times than that at the optimum Tm³⁺doping concentration.At 455 nm light excitation,the strong enhancement of the emission intensity of Tm³⁺: 1.85 ?m is attributed to the energy transfer sensitization of Mn⁴⁺ to Tm³⁺and cross relaxation between Tm³⁺and Tm³⁺.At the same time analysis found that the energy transfer of Mn⁴⁺ to Tm³⁺ in Mn⁴⁺/Tm³⁺ co-doped samples is mainly through the electric dipole-dipole interaction.In chapter 4,we mainly researched the Mn⁴⁺/Yb³⁺co-doped La₂MgTiO₆near-infrared emitting phosphor which was synthesized by co-precipitation method.In La₂MgTiO₆ matrix,the Mn⁴⁺ has a strong absorption in the range of ultraviolet light to visible light,and Mn⁴⁺has a better sensitization effect on Yb³⁺.The La₂MgTiO₆: Mn⁴⁺,Yb³⁺ luminescent materials can convert short wavelength light in the 250-550 nm region into near-infrared emission of Yb³⁺: 990 nm.We also analyzed the energy transfer sensitization mechanism of Mn⁴⁺to Yb³⁺in La₂MgTiO₆ matrix.It is also proved that the energy transfer of Mn⁴⁺ to Yb³⁺ in La₂MgTiO₆ matrix is phonon assisted energy transfer.The material is emitted at990 nm just in the most effective spectral response area of silicon solar cells.Therefore,we synthesized this luminescent material can be used as a spectral conversion layer to improve the responsiveness of silicon solar cells to the spectra of ultraviolet and visible light,thereby increasing the total photoelectric conversion rate for the solar spectrum.