Preparation And Properties Of Cr³⁺/Mn⁴⁺ Doped Deep-red And Near-infrared Luminescent Materials

Near-infrared(NIR)phosphor-converted light-emitting diodes(pc-LEDs)have many potential applications in food inspection,health management,plant growth,and night vision,where NIR phosphors are key components of the corresponding devices.Improving near-infrared phosphors is of great significance for advancing semiconductor solid-state lighting technology.Thanks to the technical and cost advantages brought about by the rapid development of white LEDs in the past two decades,NIR pc-LED technology has also been rapidly advanced in recent years,and the core components of the near-infrared phosphors have also been widely used by researchers.Development and reporting.Transition Cr³⁺and Mn⁴⁺doped deep red and near-infrared phosphors have become the focus of research due to their excellent luminescence properties,but their overall performance cannot meet people's requirements at present.This paper focuses on the design,optimization and multi-functional application of Cr³⁺and Mn⁴⁺doped phosphors.The specific work is as follows:1.A deep red emitting phosphor with an ultra-wide response range was prepared by high-temperature solid-phase sintering,and its structural formula is Ca Mg Al₁₀O₁₇:Mn⁴⁺.The absorption range spans the ultraviolet,near-ultraviolet,blue,and green light regions from 250 to 550 nm.Under the excitation of the best excitation position at 343 nm,deep-red light at 654 nm is emitted,and the quantum efficiency is as high as 86.7%.The luminous efficiency of the two pc-LED devices prepared based on Ca Mg Al₁₀O₁₇:Mn⁴⁺with 395 and 460 nm chips reached 54.3 and59.6 lm/W,respectively.The spectra of the two pc-LEDs are highly spectrum resemblance to the absorption spectra of chlorophyll A and B in plant growth photosynthesis.These indicate that the Ca Mg Al₁₀O₁₇:Mn⁴⁺phosphor can be used for plant growth LED fill light equipment.2.A luminescent material Ca₃Sc₂Si₃O₁₂:Cr³⁺with ultra-wide near-infrared emitting garnet structure was designed and prepared.Under 460 nm excitation,Ca₃Sc₂Si₃O₁₂:Cr³⁺presents an ultra-wide emission range from 650 nm to 900 nm.The weak absorption capacity of Cr³⁺is the main factor causing its undesirable luminous efficiency.Ce³⁺was introduced as a sensitizer to improve the absorption of Cr³⁺.An efficient energy transfer process from Ce³⁺to Cr³⁺can be observed within the Ca₃Sc₂Si₃O₁₂ co-doped substance with Ce³⁺and Cr³⁺.The sample with the best doping concentration has demonstrated excellent thermal stability,and the near-infrared emission intensity at 150°C can be maintained at 82%at room temperature.The NIR output power of the NIR pc-LED based on Ca₃Sc₂Si₃O₁₂:Ce³⁺,Cr³⁺and 450nm chip reached 21.65 m W@350 m A.The excellent performance of penetrating human tissues demonstrated by the near-infrared pc-LED was observed.3.Given the wide-ranging applicability of the material,this study was designed to comprehensively evaluate a series of novel NIR phosphors:Ba Mg Ga_xAl_10-xO₁₇:Cr³⁺(x=0,1,2,3).The ultra-low-temperature(4 K)fluorescence spectroscopy and decay curve results confirmed that Cr³⁺occupies the four lattice sites of Al³⁺in the matrix.Additionally,the introduction of Ga³⁺increased the full-width at half-maximum(FWHM)of the NIR spectrum from 100 to 300 nm without affecting the fluorescence efficiency;it also considerably increased spectral coverage.An experiment to evaluate the applicability of the novel NIR phosphors revealed that the sunlight-converting film prepared by applying the material combination of Ba Mg Ga₃Al₇O₁₇:0.02Cr³⁺was able to effectively promote the growth of Chlorella.In addition,the NIR pc-LED with a Ba Mg Ga₃Al₇O₁₇:0.2Cr³⁺basis and 395 nm LED chip has been proven to work well in spectral detection and night-vision technology.