Das Bikas C, Pal Amlan J
Indian Association for the Cultivation of Science, Department of Solid State Physics and Centre for Advanced Materials, Jadavpur, Kolkata 700032, India.
ACS Nano. 2008 Sep 23;2(9):1930-8. doi: 10.1021/nn800335f.
We report growth, monolayer formation, and (electrical bistability and memory phenomenon) properties of hybrid core-shell nanoparticles. While inorganic quantum dots, such as CdS or CdSe, act as the core, a monolayer of ionic organic dye molecules, electrostatically bound to the surface of functionalized quantum dots, forms the shell. We form a monolayer of the core-shell hybrid nanoparticles via a layer-by-layer electrostatic assembly process. Growth and monolayer formation of the organic-inorganic hybrid nanoparticles have been substantiated by usual characterization methods, including electronic absorption spectroscopy of dispersed solution and atomic force microscope images of scratched films. Devices based on the hybrid nanoparticles have exhibited electrical bistability and memory phenomena. From the comparison of these properties in core-shell nanoparticles and in its components, we infer that the degree of conductance switching or on/off ratio is substantially higher in the hybrid nanoparticles. Also, they (core-shell particles) provide routes to tune the bistability and memory phenomena by choosing either of the components. A monolayer of hybrid nanoparticles has been characterized by a scanning tunneling microscope tip as the other electrode. We show that a single core-shell hybrid nanoparticle can exhibit bistability with an associated memory phenomenon. Charge confinement, as evidenced by an increase in the density of states, has been found to be the mechanism of electrical bistability.
我们报告了混合核壳纳米粒子的生长、单层形成以及（电双稳性和记忆现象）特性。以硫化镉或硒化镉等无机量子点为核，通过静电作用结合到功能化量子点表面的单层离子有机染料分子形成壳层。我们通过逐层静电组装工艺形成核壳混合纳米粒子的单层。有机-无机混合纳米粒子的生长和单层形成已通过常规表征方法得到证实，包括分散溶液的电子吸收光谱和划痕薄膜的原子力显微镜图像。基于混合纳米粒子的器件表现出电双稳性和记忆现象。通过比较核壳纳米粒子及其组分的这些特性，我们推断混合纳米粒子中的电导切换程度或开/关比显著更高。此外，它们（核壳粒子）通过选择任何一种组分提供了调节双稳性和记忆现象的途径。混合纳米粒子的单层已用扫描隧道显微镜针尖作为另一电极进行了表征。我们表明单个核壳混合纳米粒子可以表现出双稳性并伴有记忆现象。态密度增加所证明的电荷限制被发现是电双稳性的机制。
