Preparation And Luminescent Properties Of Nanodiamond-based Rare Earth Hybrid Luminescent Materials

Recently,nanodiamonds(NDs)have attracted world-wide attention in optical and biomedical fields because of their chemical-physical stability,rich surface groups,low toxicity,etc.However,the luminescence of original NDs is usually very poor,which has become a huge obstacle that hinders their applications in bioimaging and lightemitting devices.Therefore,it is very important to study how to improve the luminous performance of NDs.Based on the above considerations,a series of nano-diamondbased rare earth hybrid luminescent materials were prepared by hydrothermal / solvothermal method,and their morphologies,luminescent properties and potential applications were studied.The major breakthroughs and significances of the results are listed below: 1.Nanodiamond-pyromellitic acid-rare earth(ND-PMA-RE)hybrid materialsLuminescent hybrid materials were prepared by covalently functionalizing NDs with rare earth(RE)complexes.Pyromellitic acid(PMA),as the organic sensitizer,was grafted onto amino-terminated NDs to chelate lanthanide ions(Eu3+ and Tb3+).The emission colors of the hybrid composite of ND-PMA-EuxTby can be tuned from red to orange,yellow and green by adjusting the molar ratio of Eu3+ to Tb3+(x:y = 1:0,1:1,1:5 and 0:1).ND-PMA-Eu and ND-PMA-Tb hybrid materials have a longer lifetime of 0.82 and 0.92 ms,respectively,compared to the corresponding rare earth complexes.Moreover,the luminescence of the hybrid composites exhibits remarkable photostability under ultraviolet irradiation for 60 h.As a proof-of-concept experiment,the as-synthesized ND-PMA-Eu and ND-PMA-Tb were employed as the phosphors for red and green light-emitting-diode(LED)devices with ultraviolet(UV)chips(280 nm).In addition,the codoping hybrid composites ND-PMA-Eu1Tb5 display conspicuously temperature dependent luminescent behavior from 10 K to 300 K.The energy transfer from Tb ions to Eu ions occurs during the temperature change process.Therefore,the nanodiamond-based luminescent hybrid material may find potential application in optical device.2.Nanodiamond-?-Thenoyltrifluoroacetone-rare earth hybrid materialThe ?-thienoyl trifluoroacetone(TTA)was first silylated to obtain the TTA-Si organic ligand.Luminescent hybrid materials were prepared by covalently functionalizing NDs with rare earth(RE)complexes.TTA-Si,as the organic sensitizer,was grafted onto silanized NDs to chelate lanthanide ions Eu3+.The results show that the characteristic emission of Eu ions can be obtained by excitation at 360 nm,which has a great advantage in the current device packaging process.