Combination And Photoluminescence Properties Of Carbon Dots/Rare Earth Ions Doped Luminescent Materials

Rare earth ions doped luminescent materials have comprehensive application prospects in the fields of fluorescent labeling,optical devices,ion detection and other aspects based on their unique properties.However,there are still requirements for the improvement of luminescent properties in practical applications.In this thesis,different rare earth ions doped fluoride and phosphate luminescent materials have been synthesized by hydrothermal method,and the corresponding nanocomposites were prepared through combined with carbon dots(CDs)in order to improve the luminescent performance.The phase structure,morphologies and luminescence properties of the samples were characterized by X-ray diffraction(XRD),photoluminescence spectrum(PL),Fourier transform infrared spectroscopy(FTIR),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),ultraviolet and visible spectra(UV-vis)and so on.The specific research contents were as follows:1.Carbon dots with blue light emission were prepared by hydrothermal method using 1,2,4,5-benzenetetracarboxylic acid as the carbon source.The luminescent CDs@YF3:Ln3+(Ln3+=Eu3+,Tb3+,Ce3+/Tb3+)nanocomposites were prepared through combined with CDs.The results indicate that the phase structure and morphologies of YF3 nanomaterials have almost no changed after combined with CDs and doped with different rare earth ions.However,the luminescence intensity can be significantly increased by 13,7 and 5 times after combined with CDs.2.LaF3:Ln3+and CDs@LaF3:Ln3+(Ln3+=Eu3+,Tb3+,Ce3+/Tb3+)nanocomposites were synthesized by hydrothermal method.The effects of CDs on the phase structure,morphologies and luminescence properties of the samples were investigated in detail.The results show that the phase structure of LaF3:Ln3+nanomaterials have almost no changed after combined with CDs and doped different rare earth ions,but CDs@LaF3:Ln3+nanocomposites have well dispersed and small size due to CDs preventing the nanocrystals from agglomeration.In addition,the luminescence intensity can be significantly increased by 26,32 and 2 times after combined with CDs.The mechanism of luminescence enhancement attributed to the efficient energy transfer between CDs and doped rare earth ions.3.CDs@CePO4:Tb3+nanorods were successfully obtained via a simple hydrothermal method.The effects of CDs on the phase structure,morphologies and luminescence properties of the samples were investigated in detail.Due to the combination of CDs,the emission intensity of CDs@CePO4:Tb3+nanorods have significantly increased by 50 times,compared with that of CePO4:Tb3+ nanorods,and the luminescence quantum yields enhanced from 6.8%to 14%.The possible mechanism of luminescence enhancement is discussed in detail.This study provides an effective strategy for improving the luminescence properties of other rare earth ions doped phosphate luminescent materials.