摘要
报道用“一步”合成新方法制备了CdSe/ZnSe核-壳结构的发光纳米粒子。该方法是将锌的前驱体注入表面Se富集的CdSe发光纳米粒子溶液中,通过Zn2+与Se共价键结合,从而在CdSe发光纳米粒子的表面形成ZnSe壳。分别通过X射线粉末衍射、光电子能谱、透射电镜、紫外-可见吸收光谱和光致发光光谱,对核-壳结构的发光纳米粒子的结构及光学性质进行了表征。结果表明,以较宽带隙的ZnSe在较窄带隙的CdSe纳米粒子表面形成的壳层有效地钝化了CdSe纳米粒子的表面缺陷,明显地提高了室温下CdSe纳米粒子的光致发光效率。X射线粉末衍射表明随着Zn2+的不断注入,CdSe/ZnSe的衍射峰逐渐移向ZnSe衍射峰。光电子能谱数据显示,Zn 2p的双峰分别位于1 020,1 040 eV附近,通过与体材料ZnO相比,确定为Zn2+的光电子发射,说明Zn是以共价键形式存在于CdSe纳米粒子的表面。透射电镜照片显示纳米粒子具有良好的单分散性,核-壳结构的发光纳米粒子直径较CdSe核的直径明显增加。
In recent years, nanocrystals （NCs） of semiconductor materials have been attracting considerable interest due to their size-tunable optical and electronic properties, and they have already been used as sensors, laser materials, thin film light-emitting devices （ LEDs）, and biological labels. However, because of the high surface-to-volume ratio of nanoparticles, the surface properties have significant effects on their electronic and optical properties. It is for this reason that surface modification of these particles has been the subject of extensive investigation. In this report a simple one-pet synthetic route to prepare highly luminescent CdSe/ZnSe core-shell nanocrystals was presented. A ZnSe shell around a CdSe nanoparticles was formed by the reaction of selenium-richness on the surfaces of CdSe nanopaticles with Zn^2＋ from the injected zinc stearate precursor. The core-shell structure was verified by X-ray diffraction （XRD）, X-ray photoelectron spectra （XPS）, transmission electron microscopy （TEM）, UV-vis absorption spectroscopy and photoluminescence （PL） spectroscopy, respectively. The CdSe nanoparticles capped with wider band-gap ZnSe show successful passivation to remove surface defects. The X-ray diffraction patterns of the CdSe/ZnSe core-shell nanoparticles comparing with those of the bare CdSe cores shift to a higher angle. The X-ray photoelectron spectra analysis also clearly indicated the characteristic peaks such as Zn2p3/2, Zn 2p1/2, and the Zn 2p signal detectable on the CdSe/ZnSe nanocrystals, indicating that Zn^2＋ was strongly bound to the nanocrystal＇s surface. The transmission electron microscopy micrographs of the core-shell nanoparticles show well-defined spherical particles with larger diameters than those of the particles of the parent material. Consequently photoluminescence efficiencies improved observably.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2006年第3期383-387,i0002,共6页
Chinese Journal of Luminescence
基金
国家"863"计划(2002AA302203)
中国科学院重大基金(2002CD713802)资助项目
关键词
核-壳纳米粒子
钝化
表面缺陷
光致发光
core-shell nanoparticles
passivate
surface defect
photoluminescence
