Synthesis,spectral Modification And Performance Enhancement Of Mn⁴⁺-doped Fluoroaluminate/fluorogallate Red Phosphor

As a new generation of green lighting source,white LED,which is widely used in indoor and outdoor lighting,backlight display and other fields,has developed rapidly with its advantages of energy saving,long life,no pollution,etc.The current commercial WLEDs are mainly made of blue Ga N or In Ga N chips and Y₃Al₅O₁₂:Ce³⁺yellow phosphors,but there are problems with high color temperature(>6000 K)and low color rendering index(<75).Adding a certain proportion of red phosphor to the device to form a"blue-yellow-red"three-color system can achieve high-quality warm white light emission with low color temperature and high color rendering index.The absorption wavelength of the Mn⁴⁺doped fluoride red light material matches that of the blue chip and the emitted light is in the sensitive red light region of the human eye.At the same time,it has the advantages of simple preparation process,high red light color purity,and good stability.It is a class red light material suitable for commercial blue light chips.Mn⁴⁺has different spectral positions in different crystal field environments,and the corresponding red light materials also have different luminescence properties.In this paper,starting from three different fluoroaluminate and fluorogallate substrates,aiming to control the emission spectrum of Mn⁴⁺,XRD,SEM,XRF,spectrometer and other testing equipment are used to measure the phase,morphology,structure,and doping of the material.The impurity concentration,thermal stability,fluorescence lifetime quantum efficiency,and optical properties have been systematically studied.The main research contents are as follows:(1)Using Rb₂Na AlF₆ with double perovskite structure as the matrix,through the unequal exchange between Mn⁴⁺and Al³⁺,the highly symmetrical[MnF₆]octahedron inside the matrix is distorted to achieve the purpose of regulating the emission spectrum of the material.Finally,a warm white light device for lighting with a color temperature of 3870 K and a color rendering index of 87.0 was prepared.(2)Through the replacement of alkali metal ions and central ions,another double perovskite-type red light material Rb₂KGaF₆:Mn⁴⁺with a regular octahedral morphology was constructed.Compared with Rb₂Na AlF₆:Mn⁴⁺,Rb₂KGaF₆:Mn⁴⁺has an enhanced spectral intensity which is"blue shift"of position,a better thermal stability and a higher quantum efficiency.The white light LED device prepared by compounding the red light material and commercial YAG yellow powder on a Ga N chip has a color temperature of 3824 K and a color rendering index of 90.2.(3)A red light material Rb₂LiGaF₆:Mn⁴⁺who has Ga³⁺double lattice was synthesized,which The zero phonon line(ZPL)intensity far exceeds the phonon vibration band.Rb₂Li GaF₆:Mn⁴⁺has excellent thermal stability and high internal quantum efficiency and a stronger luminous intensity than the above two materials.The color gamut of a WLEDs based on this material,?-sialon green phosphor and Ga N chip is 105%of NTSC.The color temperature of the lighting LED prepared with YAG and Ga N chips is 3913 K,and the color rendering index reaches 92.6.