Preparation And Luminescence Properties Of Mn⁴⁺ Doped Red Phosphor-in-Glass

More and more attention has been paid to the research and development of LEDs for plant lighting.The organic resin used in the traditional LED packaging process has poor thermal stability,poor thermal conductivity,and susceptibility to ultraviolet oxidation,resulting in drift of the color coordinate of the LED device,reduced luminous efficiency,and shortened service life.Phosphor-in-glass?PiG?is considered a viable alternative to organic resin.PiG can be prepared by sintering the mixture of phosphor and glass powder below 800°C.It not only has the high permeability and strong mechanical properties of glass,but also maintains the luminous performance of phosphor.In this paper,we first synthesized Sr₂Mg Al₂₂O₃₆:Mn⁴⁺?abbreviated asSMA:Mn4+?,Ca_14-xSr_xZn₆Al₁₀O₃₅:Mn4+?CSZA:Mn4+?,CaAl₁₂O₁₉:Mn⁴⁺(CA:Mn⁴⁺),NaLaMgWO₆:Mn⁴⁺(NLMW:Mn⁴⁺)phosphors through the traditional high temperature solid phase method.Then,these phosphors and silicate glass powder?SiO₂-Al₂O₃-Zn O-BaO-B₂O₃?were mechanically mixed,and the corresponding PiG materials were prepared by low-temperature co-sintering method.Finally,the structure,composition,luminescence properties and thermal stability of phosphors and corresponding PiG materials were systematically analyzed.The results showed that four series of PiG samples including SMA:Mn4+-PiG,CSZA:Mn4+-PiG,CA:Mn4+-PiG and NLMW:Mn4+-PiG were successfully prepared.These PiG samples all have a certain degree of transparency,which not only maintain the amorphous nature and mechanical properties of the glass,but also maintain the inherent crystal structure and luminescent properties of the phosphor.All phosphor glass samples have strong absorption in the range of 250-550 nm and can be excited by ultraviolet light or blue light.They exhibit strong red light emission at 600-750 nm due to the ²E?⁴A₂ spin-forbidden transition of Mn⁴⁺ion.Compared with phosphors,the internal and external quantum efficiencies and lifetimes of corresponding PiG samples are lower.Compared with SMA:Mn4+and CA:Mn4+phosphors,the corresponding PiG samples have a certain degree of improvement in thermal stability.The phosphor glass and the ultraviolet or blue chip were combined to encapsulate the LED device,and the emission intensity of the red region of the LED device was adjusted by changing the phosphor doping concentration,the thickness of the PiG sample,and the driving current.Therefore,Mn⁴⁺-doped red phosphor glass has the potential to replace the organic fluorescence conversion layer.Based on the perfect overlap of the emission spectrum of Pi G sample and the absorption spectrum of photosensitive pigment,red LEDs packaged with blue or ultraviolet chips are expected to be used in the field of plant lighting.