Preparation of Semiconductor Nanoparticle-Assembled Layers Having Desired Photoluminescent Properties

我们开发了新的策略，二氧化硅包覆的半导体纳米粒子复合材料，表现出所需的光化学性能的制备。纳米复合材料的颗粒层可以通过使用逐层累积技术来制备。采用尺寸选择性光刻技术对所制备的纳米颗粒进行了尺寸选择性光刻，将其修饰为铃铛形状。首先，对二氧化硅包覆的硒化镉（SiO2/CdSe）纳米颗粒进行尺寸选择性光刻，以精确控制其光致发光特性。虽然所制备的SiO2/CdSe没有表现出光致发光，SiO2/CdSe的尺寸选择性光刻的应用导致的带隙发射的发展，程度被增强与光刻的进展。部分光刻的SiO2/CdSe纳米颗粒薄膜在光刻区域产生了强烈的CdSe带隙发射，而其余的SiO2/CdSe纳米颗粒薄膜没有表现出明显的带隙发射。 关于我们 可检测的光致发光，导致在UV照射下形成清晰的光致发光图像。该技术使得可以通过使用单个源材料用具有各种波长的单色光照射来产生单色光致发光图像。其次，通过添加三烷基胺，其程度取决于它们的分子尺寸，使铃铛形二氧化硅包覆的硫化镉纳米颗粒（SiO2/CdS）的光致发光猝灭。这些现象归因于猝灭剂分子从本体溶液中通过叮当状纳米颗粒的SiO2壳层的孔隙进入空隙空间的分子尺寸选择性渗透。由于颗粒中复合位点的数量较少，所制备的叮当状半导体纳米颗粒似乎是有希望的光能转换材料，因为这些复合位点表现出强烈的光致发光。铃铛状的SiO2/CdS颗粒比市售的块状CdS颗粒表现出更高的光催化活性。特别是对于硝基苯的光还原反应，通过改变光催化剂的纳米结构，可以改变还原产物的产率和选择性。少

We developed novel strategies of the preparation of silica-coated semiconductor nanoparticle composites which exhibited the desired photochemical properties. The particulate layers of the nanocomposites could be prepared by using layer-by-layer accumulation techniques. The nanostructure of the obtained particles was modified to the shape of the jingle bell by using the size-selective photoetching technique.First, the size-selective photoetching was applied to silica-coated cadmium selenide (SiO2/CdSe) nanoparticles to precisely control their photoluminescence properties. Although as-prepared SiO2/CdSe did not exhibit photoluminescence, the application of size-selective photoetching to SiO2/CdSe resulted in the development of the band gap emission, the degree being enhanced with progress of the photoetching. Partial photoetching of SiO2/CdSe nanoparticle films produced intense band gap emission of CdSe at the photoetched area, while the remainder of the SiO2/CdSe films did not exhibit d … More etectable photoluminescence, resulting in the formation of a clear photoluminescence image under UV irradiation. This technique makes it possible to produce a multicolor photoluminescence image by irradiation with monochromatic lights having various wavelengths using a single source material. Second, the photoluminescence of the jingle-bell-shaped silica-coated cadmium sulfide nanoparticles (SiO2/CdS) was quenched by the addition of trialkylamines, the degree being dependent on their molecular size. These facts were attributable to the molecular-size-selective penetration of quencher molecules from the bulk solution to the void space through the pores of the SiO2 shell of the jingle-bell-shaped nanoparticles.The prepared jingle-bell-shaped semiconductor nanoparticles seemed to be promising materials for light energy conversion owing to the less amount of recombination sites in the particles, because these exhibited the strong photoluminescence. The jingle-bell-shaped SiO2/CdS particles exhibited much higher photocatalytic activities than those of commercially available bulk CdS particles. For the photoreduction of nitrobenzene, especially, the yield and selectivity of the reduction products could be varied by changing the nanostructure of photocatalysts used. Less