Synthesis Of Gd₂O₂S:Yb³⁺/Er³⁺/Tm³⁺ Upconversion Luminescence Materials By Sol-gel Method

Rare earth(RE) ion-doped upconversion luminescence(UCL) materials are one of the hotspots of research because of their widely application in the fields of solid color three-dimensional display, backlight and liquid crystal display, etc. Oxysulfide has a wide band gap, and has a high light absorption and energy transfer efficiency when used as a luminous matrix. Upconversion luminescence materials of Gd2O2S:Yb3+/Er3+/Tm3+ were prepared by sol-gel method, the effects of calcination temperature, holding time, chelating agent type and the doping concentration of rare earth ions on the crystal structure and luminescence properties of the materials were investigated. Main contents and results are as follows:1.Gd2O2S:Yb3+,Er3+ phosphors were prepared by sol-gel method, the crystal structure,morphology and UCL properties were analyzed and characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and fluorescent spectroscopy analysis. Under the excitation of 980 nm laser diode(LD), the emission specta of the samples appeared green and red emissions,which were located at 528 nm,547 nm and 668 nm, corresponding to the2H11/2?4I15/2 transition,4S3/2?4I15/2 transition and 4F9/2?4I15/2 transition of Er3+ ions respectively. Through the analysis of power curve and energy level matching conditions, it can be illustrated that the upconversion luminescence mechanism of Er3+,Yb3+ co-doped system and the green upconversion emission which centered at 547 nm was mainly two-photon process,the red emission of 668 nm was also mainly two-photon process.2.Gd2O2S:Yb3+,Tm3+ phosphors were synthesized by sol-gel technology,the crystal structure, morphology and luminescence properties of the samples were tested and characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and fluorescent spectroscopy analysis. Under 980 nm LD excitation, upconversion luminescence of Tm3+ ions was observed, the blue light emitting peak of 480 nm, the green light emitting peak of 547 nm and the red light emitting peak of 651 nm, corresponding to the 1G4?3H6transition, 1D2?3H5 transition and 1G4?3F4 transition of Tm3+ ions respectively. According to the analysis of power curve and energy level matching conditions,the upconversion luminescence mechanism of Tm3+,Yb3+ co-doped system was discussed, which showed that the blue emission of 480 nm and the red emission of 651 nm were mainly three-photon process,the green emission of 547 nm was mainly two-photon process.3.Based on the synthesis of the above two types of upconversion luminescence materials, Gd2O2S:Yb3+,Er3+,Tm3+ phosphors were prepared by sol-gel process, the crystalmorphology and luminescence properties of the samples were studied by XRD, SEM and UCL.Under the 980 nm LD excitation, the peak of the upconversion luminescence of the samples can be observed, they were the blue light at 480 nm, the green light at 547 nm and the red light at 668 nm. By the power curve analysis as well as energy level matching conditions, the upconversion luminescence mechanism of Er3+,Tm3+,Yb3+ three mixture system was explored, which indicated that the blue emission of 480 nm was mainly three-photon process, the green emission of 547 nm and the red emission of 668 nm were mainly two-photon process.