摘要
利用有机相法合成Nd~(3+)掺杂CdSe纳米晶(CdSe:Nd),通过X射线粉末衍射(XRD)、透射电镜(TEM)、紫外吸收光光谱及荧光光谱表征,证明Nd~(3+)已经成功掺入到CdSe的晶格中。与纯CdSe纳米晶相比,CdSe:Nd纳米晶的结构仍为立方晶型,且形貌近似球形,均匀分散,粒径约为2~4 nm。紫外吸收峰和荧光发射峰都发生红移,而且掺杂后的CdSe:Nd纳米晶量子产率也提高,这可能是由于掺杂Nd~(3+)引入了新的杂质能级,带隙减小。为了实现CdSe:Nd纳米晶的可加工性和功能性,通过微乳法合成SiO_2壳包覆的CdSe:Nd纳米球(CdSe:Nd@SiO_2纳米球),CdSe:Nd@SiO_2纳米球呈均匀球形,直径约为100~115 nm,并且包壳后的CdSe:Nd@SiO_2纳米球发射峰(581 nm)与CdSe:Nd纳米晶(598 nm)相比,发光强度提高且发射峰蓝移,蓝移约为17 nm,可能是因为SiO_2壳可以减少纳米晶表面的非辐射跃迁以及改善表面缺陷导致的。
CdSe: Nd nanocrystals(CdSe: Nd NCs) were synthesized via organic phase method. The objective of this research was to investigate structure,microstructure,optical properties and possible luminescence mechanism of CdSe: Nd and CdSe: Nd@ Si O2. It is confirmed that Nd3 +is successfully incorporated into the crystal lattice of CdSe through XRD,TEM,UV-visible absorption spectroscopy and fluorescence emission. Compared with pure CdSe NCs,CdSe: Nd NCs still have a cubic crystal structure,the lattice constant of CdSe and CdSe: Nd NCs is 0. 605 and 0. 609 nm,respectively. The lattice of CdSe: Nd constant increases,it may be due to the ionic radius of Nd3 +is larger than Cd2 +.When Nd3 +is incorporated into the crystal lattice of CdSe: Nd NCs,which results in dilation of crystal lattice. CdSe: Nd NCs are monodisperse and spherical particles with an average diameter of 2-4 nm. Both absorption spectrum and emission spectrum red-shift,and the quantum yields of the CdSe:Nd NCs also increase,which may be due to the introduction of new impurity levels and the decrease of the band gap. To enhance the stability and functionality of CdSe: Nd NCs,CdSe: Nd NCs were coated with Si O2(CdSe: Nd@ Si O2 spheres) and the core-shell Si O2-coated CdSe: Nd NCs(CdSe:Nd@ Si O2) were prepared via the micro-emulsion method. XRD patterns show that the patterns ofCdSe: Nd@ Si O2 contain the characteristic peak of CdSe: Nd NCs,which proves that CdSe: Nd has entered in the Si O2 shell successfully. CdSe: Nd NCs are uniform spherical with an average diameter of 100-115 nm,and CdSe: Nd NCs can be clearly seen in the Si O2 shell. The fluorescence emission of CdSe: Nd@ Si O2(581 nm) shows a blue-shift compared with CdSe: Nd NCs(598 nm),possibly because of altered surface properties and reduction of nonradiative transitions.
引文
[1]HUANG H Q,LIU J L,HAN B F,et al..Cell labeling and cytotoxicity of aqueously synthesized Cd Te/Cd S/Zn S coreshell-shell quantum dots by a water bath-hydrothermal method[J].J.Lumin.,2012,132(4):1003-1009.
[2]LIU P,WANG Q,LI X.Studies on Cd Se/l-cysteine quantum dots synthesized in aqueous solution for biological labeling[J].J.Phys.Chem.C,2009,113:7670-7676.
[3]KUMAR R,NYK M,OHULCHANSKYY T Y,et al..Combined optical and MR bioimaging using rare earth ion doped Na YF4nanocrystals[J].Adv.Funct.Mater.,2009,19(111):853-859.
[4]LIU N,ZHOU W Z,XU L,et al..Enhanced luminescence of Zn Se∶Eu3+/Zn S core-shell quantum dots[J].J.NonCryst.Solids,2012,358(17):2353-2356.
[5]KUNDU S,KAR A,PATRE A.Morphology dependent luminescence properties of rare-earth doped lanthanum fluoride hierarchical microstructures[J].J.Lumin.,2012,132(6):1400-1406.
[6]SARAVANAN L,PANDURANGAN A,AYAVEL R.Synthesis and luminescence enhancement of cerium doped Cd S nanocrystals[J].Mater.Lett.,2012,66(1):343-345.
[7]ZEBARDASTAN N,KHANMIRZAEI M H,RAMESH S,et al..Performance enhancement of poly(vinylidene fluoride-cohexafluoro propylene)/polyethylene oxide based nanocomposite polymer electrolyte with Zn O nanofiller for dye-sensitized solar cell[J].Org.Electron.,2017,49:292-299.
[8]AN Q Z,FASSL P,HOFSTETTER Y J,et al..High performance planar perovskite solar cells by Zn O electron transportlayer engineering[J].Nano Energy.2017,39:400-408.
[9]WANGA Y F,SONGB J M,NIUA G Z,et al..Fabrication and post-chemical-etched surface texturing of H and Ti codoped Zn O film for silicon thin-film solar cells[J].Ceram.Int.,2017,43(12):9382-9389.
[10]MARTN-RODRGUEZ R,GEITENBEEK R,MEIJERINK A.Incorporation and luminescence of Yb3+in Cd Se nanocrystals[J].J.Am.Chem.Soc.,2013,135(37):13668-13671.
[11]HAMNABARD N,HANIFEHPOUR Y,JOO S W.Effectiveness of Nd doping and graphene oxide modification on electrochemical performance of Cd Se nanorod material[J].J.Ind.Eng.Chem.,2017,49:88-98.
[12]LI H,SUN Y Q,XU L,et al..Tunable luminescence in full color region based on Cd Se/EuxSeyhybrid nanocrystals[J].RSC Adv.,2013,3:22849-22852.
[13]XU X M,ZHOU L Y,ZHANG Q,et al..Synthesis and luminescence properties of Eu2+-doped Cd Se nanocrystals[J].RSC Adv.,2013,3:24593-24596.
[14]LI F I,YEH C S.Synthesis of Gd doped Cd Se nanoparticles for potential optical and MR imaging applications[J].J.Mater.Chem.,2010,20(11):2079-2081.
[15]SUNIL K,NIT U K,SUDHANSHU S,et al..Doping studies of Tb(terbium)and Cu(copper)on Cd Se nanorods[J].Colloids and Surf.A:Physicochem.Eng.Aspects,2011,389:1-5.
[16]KHATAEE A R,FATHINIA S,FATHINIA M,et al..Synthesis,characterization and photocatalytic properties of nanostructured Sm-doped Cd Se[J].Current Nanosci.,2013,9(6):780-786.
[17]王益林,杨昆,潘华桥,等.高质量Cd Se量子点的水相制备与表征[J].高等学校化学学报,2012,33(12):2604-2608.WANG Y L,YANG K,PAN H J,et al..Preparation and characterization of high quality Cd Se quantum dots in aqueous solution[J].Chem.J.Chin.Univ.,2012,33(12):2604-2608.(in Chinese)
[18]黄科,李玲,黄国英,等.基于氢化物发生技术的Cd Se量子点水相制备新方法研究及其用于银的高灵敏传感分析[J].发光学报,2017,38(5):575-579.HUANG K,LI L,HUANG G Y,et al..Aqueous synthesis of Cd Se qumantum dots by hydride generation and its applications in sensitive analysis of silver[J].Chin.J.Lumin.,2017,38(5):575-579.(in Chinese)
[19]安娜,卢睿,马昊玥,等.Cd Se/Cd S核壳量子点复合材料合成及其在白光发光二极管中的应用[J].发光学报,2017,38(8):1004-1009.AN N,LU R,MA H Y,et al..Synthesis of Cd Se/Cd S core/shell quantum dots luminescent microspheres and their application for WLEDs[J].Chin.J.Lumin.,2017,38(8):1004-1009.(in Chinese)
[20]WU Y H,QIAO P W,QIU J J,et al..Magnetic nanostructures grown on vertically aligned carbon nanotube templates[J].Nano Lett.,2002,2(2):161-164.
[21]LEE A F,BADDELEY C J,HARDACRE C,et al..Structural and catalytic properties of novel Au/Pd bimetallic colloid particles:EXAFS,XRD,and Acetylene coupling[J].J.Phys.Chem.,1995,99(16):6096-6102.
[22]GUO X,LI Y Y,SHEN D H,et al..Immobilization of cobalt porphyrin on Ce O2@Si O2core-shell nanocrystals as a novel catalyst for selective oxidation of diphenylmethane[J].J.Mol.Catal.A:Chem.,2013,367:7-11.
[23]SAADATKHAH N,RIGAMONTI M G,BOFFITO D C,et al..Spray dried Si O2WO3/Ti O2and Si O2vanadium pyrophosphate core-shell catalysts[J].Powder Technol.,2017,316:434-440.
[24]CORREA-DURATE M A,GIERSIG M,LIZ-MARZAN L M.Stabilization of Cd S semiconductor nanocrystals against photodegradation by a silica coating procedure[J].Chem.Phys.Lett.,1998,286(5-6):497-501.
[25]TAPEC R,ZHAO X,TAN W J.Development of organic dye-doped silica nanocrystals for bioanalysis and biosensors[J].Nanosci.Nanotechnol.,2002,2:405.
[26]翟雪松,刘世虎,范柳燕,等.强上转换发光的Li Lu1-xYbxF4∶Tm@Li Gd F4核壳纳米晶的制备[J].发光学报,2017,38(9):1150-1154.ZHAI X S,LIU S H,FAN L Y,et al..Preparation of Li Lu1-xYbxF4∶Tm@Li Gd F4core-shell nanocrystals with enhanced upconversion luminescence[J].Chin.J.Lumin.,2017,38(9):1150-1154.(in Chinese)
[27]STBER W,FINK A,BOHN E.Controlled growth of monodisperse silica spheres in the micron size range[J].J.Colloid Interf.Sci.,1968,26:62-69.
[28]CORREA-DUARTE M A,GIERSIG M,LIZ-MARZN L M.Stabilization of Cd S semiconductor nanocrystals against photodegradation by a silica coating procedure[J].Chem.Phys.Lett.,1998,286:497-501.
[29]ROGACH A L,NAGESHA D,OSTRANDER J W,et al..“Raisin bun”-type composite spheres of silica and semiconductor nanocrystals[J].Chem.Mater.,2000,12:2676-2685.
[30]SELVAN S T,TAN T T,YING J Y.Silica-coated Cd Se quantum dots with efficient photoluminescence[J].Adv.Mater.,2005,17:1620-1625.
[31]YI D K,SELVAN S T,LEE S,et al..Silica-coated nanocomposites of magnetic nanocrystals and quantum dots[J].J.Am.Chem.Soc.,2005,127:4990-4991.
[32]TENG F,TIAN Z,XIONG G,et al..Preparation of Cd S-Si O2core-shell particles and hollow Si O2spheres ranging from nanometers to microns in the nonionic reverse microemulsions[J].Catal.Today,2004,93-95:651-657.
[33]RAOLA O E,STROUSE G F.Synthesis and characterization of Eu-doped cadmium selenide nanocrystals[J].Nano Lett.,2002,2(12):1443-1447.
[34]PARK J Y,JEONG D W,LIM K M.Multimodal luminescence properties of surface-treated Zn Se quantum dots by Eu[J].Appl.Surf.Sci.,2017,415:8-13.
[35]戴艳,侯永可,龙志奇,等.掺杂纳米氧化铈紫外屏蔽材料的表征与性能[J].中国稀土学报,2011,29(2):196-200.DAI Y,HOU Y K,LONG Z Q,et al..Characterization and UV-shielding properties of doped ceria nanocrystals[J].J.Chin.Soc.Rare Earths,2011,29(2):196-200.(in Chinese)
[36]MOU P,MATHEWS N R,MORALES ERIK R,et al..Synthesis of Eu+3doped Zn S nanocrystals by a wet chemical route and its characterization[J].Opt.Mater.,2013,35:2664-2669.
[37]LANG J H,WANG J Y,ZHANG Q,et al..Chemical precipitation synthesis and significant enhancement in photocatalytic activity of Ce-doped Zn O nanocrystals[J].Ceram.Int.,2016,42(12):14175-14181.
[38]刘月,余林,魏志钢,等.稀土金属掺杂对锐钛矿型Ti O2光催化活性影响的理论和实验研究[J].高等学校化学学报,2013,34(2):434-440.LIU Y,YU L,WEI Z G,et al..Theoretical and experimental studies on photocatalytic potential of rare earth doped anatase Ti O2[J].Chem.J.Chin.Univ.,2013,34(2):434-440.(in Chinese)
[39]LANG J H,ZHANG Q,HAN Q,et al..The study of structural and optical properties of(Eu,La,Sm)codoped Zn O nanoparticles via a chemical route resulting in the bandgap narrowing[J].Mater.Chem.Phys.,2017,194:29.
[40]MA X Y,WANG Z.The optical properties of rare earth Gd doped Zn O nanocrystals[J].Mater.Sci.Semicond.Proc.,2012,15:227-231.
[41]尤晓刚,贺蓉,高峰,等.核/壳型Cd Te@Si O2荧光纳米复合粒子的制备与表征[J].化学学报,2007,65(6):561-565.YOU X G,HE R,GAO F,et al..Preparation and characterization of Cd Te@Si O2Core/Shell luminescent composite nanocrystals[J].Acta Chim.Sinica,2007,65(6):561-565.(in Chinese)
[42]宁振动,张纪梅,魏君,等.反相微乳液法制备Cd Te@Si O2荧光微球及其荧光性能研究[J].天津工业大学学报,2012,31(1):49-52.NING Z D,ZHANG J M,WEI J,et al..Cd Te@Si O2particles prepared via reverse microemulsion method and its fluorescence properties[J].J.Tianjin Polytech.Univ.,2012,31(1):49-52.(in Chinese)
[43]SONG H Y,LEEM Y M,KIM B G,et al..Si O2-coated Zn S submicrospheres with enhanced thermal stability and photoluminescence[J].Mater.Sci.Eng.,2007,B143:70-75.