Far-red Luminescent Materials And Devices For Phototherapy

This thesis is oriented towards the application of plant light control development,photobiomodulation（Photobiomodulation,PBM）treatment and vision health applications to develop Cr³⁺activated(Y_0.75Gd_0.25)₃(Ga_0.75Sc_0.25)₅O₁₂ fluorescent materialsandβ-Ga₂O₃ fluorescent materials.Synthesis,luminious performance were deeply studied,and far-red emitting LED devices were encapsulated.After that,we further carried outpreliminary application research about PBM effects.The main research results obtained in this paper are as follows:（1）The luminescence band and luminescence performance of（Y,Gd）₃（Ga,Sc）₅O₁₂:Cr³⁺phosphor have been deeply optimized.After optimization experiments,the(Y_0.75Gd_0.25)₃[(Ga_0.75Sc_0.25)_0.95Cr_0.05]₅O₁₂ phosphor sintered at 1400℃for 6h has the strongest 730nm far-red light emission,which is blue at 450nm The FWHM of the emitted light under excitation is 120nm,covering the absorption spectrum of cells.The integrated luminescence intensity at 150℃maintained 80%of which at room temperature with no obvious shift at peak positions.The internal quantum efficiency and external quantum efficiency of(Y_0.75Gd_0.25)₃[(Ga_0.75Sc_0.25)_0.95Cr_0.05]₅O₁₂phosphors were measured to be 44.90%and 20.88%respectively.Devices were fabricated with the phosphor and blue light chip which exhibit a maxim photoelectric conversion efficiency up to 30%.When cultivated with irradiation of the mentioned device,retinal cells of mice were marvelously repaired.（2）The synthesis parameters and compositions ofβ-Ga₂O₃:Cr³⁺phosphors were optimized thoroughly to achieve a 730nm peaked broadband emission and matching the cell absorption spectrum.Conclued from these results,β-(Ga_0.98Cr_0.02)₂O₃ sintered at 1400℃for 5h with addition of 2 wt.%NHF₄F shows best luminescence performance.The obtained phosphor has good crystallinity,the crystal grain size is about 10μm,and it presents complete and clear columnar crystals stacked with layers,and the shape is complete and regular.It is measured that its luminous intensity can still maintain 80%of its room temperature luminous intensity at 180°C.Using optimizedβ-(Ga_0.98Cr_0.02)₂O₃ phosphor and blue LED chip packaged far-red light device,the radiant flux can reach 10.0mW under 200mA direct current.