金属离子对CdS量子点/聚酰胺-胺树形分子纳米复合材料光致发光性能的影响  

Effects of Metallic Ions on the Photoluminescence Properties of CdS Quantum Dots/Poly(amidoamine) Dendrimer Nano-composites

作　　者：丛日敏[1] 罗运军[2] 于怀清[1] 

机构地区：[1]山东理工大学材料科学与工程学院,淄博255049 [2]北京理工大学材料科学与工程学院,北京100081

出　　处：《无机化学学报》2007年第8期1347-1352,共6页Chinese Journal of Inorganic Chemistry

基　　金：北京理工大学基础研究基金资助项目(No.BIT-UBF-200504E4203);山东理工大学科技博士基金资助项目(No.4041-406038)。

摘　　要：以聚酰胺-胺树形分子为模板制备了分散好、尺寸均匀的CdS量子点,并用分光光度滴定法研究了Cd2+、Zn2+、Pb2+、Cu2+、Mn2+几种金属离子对其光致发光性能的影响。发现不同离子对CdS量子点的发光性能影响不同:Cd2+和Zn2+使量子点荧光增强,Pb2+、Cu2+和Mn2+使其荧光有不同程度淬灭。这归因于金属离子对CdS量子点表面的修饰作用。Cd2+能减少由S2-悬键构成的非辐射复合中心,增强树形分子对量子点表面缺陷的钝化作用,并能在量子点周围形成类肖特基能垒,从而显著增大CdS量子点的光致发光效率。由于ZnS与CdS的晶格参数非常接近,Zn2+能起到与Cd2+类似的作用,使CdS量子点的发光效率大大增强。Pb2+和Cu2+能取代Cd2+在CdS量子点表面生成窄带隙的壳层,对其发光有很强的淬灭作用。由于块体PbS的带隙比块体CuS窄,故Pb2+的淬灭能力强于Cu2+。Mn2+能破坏Cd2+与PAMAM树形分子的配位键,降低树形分子对CdS量子点表面缺陷的钝化作用,且其本身在量子点表面构成了新的荧光淬灭中心,但Mn2+也能形成较弱的类肖特基能垒,故对量子点的发光淬灭作用较弱。　CdS quantum dots（QDs） were prepared using poly（amidoamine） （PAMAM） dendrimer template,and eff-ects of such metallic ions as Cd^2＋,Zn^2＋,Pb^2＋,Cu^2＋,Mn^2＋ on the photoluminescence（PL） properties of CdS QDs were studied using spectrophotometric titration. The results show that Cd^2＋ and Zn^2＋ ions enhance the PL intensity of CdS QDs,while Pb^2＋,Cu^2＋ and Mn^2＋ ions quench it. These are attributed to the surface modification of metallic ions on CdS QDs. Excess Cd^2＋ ions can reduce the non-recombination centres,increase the passivation of PAMAM dendrimers on the surface of CdS QDs,and form a Schottky-like barrier which enhances the PL efficiency greatly. Excess Zn^2＋ ions can also increase the PL intensity markedly in the same way as Cd^2＋ ions because of their similar lattice parameters. However,a PbS or CuS shell on CdS QDs emerges due to the substitution of Cd^2＋,which leads to the decrease of band-edge emitting of CdS QDs. And the quenching effect of Pb2＋ is stronger than Cu^2＋. The coordination between Cd^2＋ and dendrimers can be damaged by Mn^2＋ ions,which results in weaker passivation of the QDs surface detects. Since Mn^2＋ ions themselves are new quenching centres,the quenching effect is mild in spite of a lower-energy Schottky-like barrier formed by Mn^2＋ ions.

关 键 词：CDS量子点 聚酰胺-胺树形分子 光致发光 金属离子 表面修饰 

分 类 号：O614.242[理学—无机化学]