| 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 |
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| 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。 |
| 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 |
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| Abstract: CdS quantum dots(QDs) were prepared using poly(amidoamine) (PAMAM) dendrimer template， and eff-ects of such metallic ions as Cd2+， Zn2+， Pb2+， Cu2+， Mn2+ on the photoluminescence(PL) properties of CdS QDs were studied using spectrophotometric titration. The results show that Cd2+ and Zn2+ ions enhance the PL intensity of CdS QDs， while Pb2+， Cu2+ and Mn2+ ions quench it. These are attributed to the surface modification of metallic ions on CdS QDs. Excess Cd2+ 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 Zn2+ ions can also increase the PL intensity markedly in the same way as Cd2+ ions because of their similar lattice parameters. However， a PbS or CuS shell on CdS QDs emerges due to the substitution of Cd2+， which leads to the decrease of band-edge emitting of CdS QDs. And the quenching effect of Pb2+ is stronger than Cu2+. The coordination between Cd2+ and dendrimers can be damaged by Mn2+ ions， which results in weaker passivation of the QDs surface detects. Since Mn2+ ions themselves are new quenching centres， the quenching effect is mild in spite of a lower-energy Schottky-like barrier formed by Mn2+ ions. |
| Keywords: CdS QDs poly(amidoamine) dendrimer photoluminescence metallic ions surface modification |
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| 丛日敏,罗运军,于怀清.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[J].无机化学学报,2007,23(8):1347-1352. |
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