Health Research Institute, National Institute of Advanced Industrial Science and Technology, Midorigaoka, Ikeda-city, Osaka 563-8577, Japan.
Langmuir. 2011 Aug 2;27(15):9535-40. doi: 10.1021/la201213c. Epub 2011 Jul 6.
A silanization technique of hydrophobic quantum dots (QDs) was applied to SiO(2)-coated CdSe/Cd(x)Zn(1-x)S QDs to precisely control the SiO(2) shell thickness and retain the original high photoluminescence (PL) properties of the QDs. Hydrophobic CdSe/Cd(x)Zn(1-x)S core-shell QDs with PL peak wavelengths of 600 and 652 nm were prepared by a facile organic route by using oleic acid (OA) as a capping agent. The QDs were silanized by using partially hydrolyzed tetraethyl orthosilicate by replacing surface OA. These silanized QDs were subsequently encapsulated in a SiO(2) shell by a reverse micelles synthesis. The silanization plays an important role for the QDs to be coated with a homogeneous SiO(2) shell and retain a high PL efficiency in water. Transmission electron microscopy observation shows that the shells are 1-9 nm with final particle sizes of 10-25 nm, depending on the initial QD size. In the case of short reaction time (6 h), the QDs were coated with a very thin SiO(2) layer because no visible SiO(2) shell was observed but transferred into the water phase. The silica coating does not change the PL peak wavelength of the QDs. The full width at half-maximum of PL was decreased 4 nm after coating for QDs emitting at both 600 and 652 nm. The PL efficiency of the SiO(2)-coated is up to 40%, mainly determined by the initial PL efficiency of the underlying CdSe/Cd(x)Zn(1-x)S QDs.
一种疏水性量子点（QD）的硅烷化技术被应用于 SiO2 涂层的 CdSe/Cd(x)Zn(1-x)S QD 上，以精确控制 SiO2 壳层的厚度并保留 QD 的原始高光致发光（PL）性能。PL 峰波长分别为 600nm 和 652nm 的疏水性 CdSe/Cd(x)Zn(1-x)S 核壳 QD 是通过简便的有机路线制备的，使用油酸（OA）作为封端剂。通过用部分水解的正硅酸乙酯取代表面 OA，对 QD 进行硅烷化。这些硅烷化的 QD 随后通过反胶束合成被包封在 SiO2 壳中。硅烷化在 QD 被均匀的 SiO2 壳包覆并在水中保持高 PL 效率方面起着重要作用。透射电子显微镜观察表明，壳层厚度为 1-9nm，最终粒径为 10-25nm，这取决于初始 QD 的尺寸。在短反应时间（6h）的情况下，由于没有观察到可见的 SiO2 壳，而是转移到水相，因此 QD 被包覆了非常薄的 SiO2 层。SiO2 涂层不会改变 QD 的 PL 峰波长。对于在 600nm 和 652nm 处发射的 QD，PL 的半峰全宽减小了 4nm。SiO2 涂层的 PL 效率高达 40%，主要由底层 CdSe/Cd(x)Zn(1-x)S QD 的初始 PL 效率决定。
