Optical Properties of Quantum Dots Doped Mesoporous AlPO4 Glasses

半导体量子点和介孔玻璃是两种典型的纳米结构材料。半导体量子点材料因为其独特的量子限域效应和尺寸相关的光学性质得到了大量的研究。介孔玻璃的纳米多孔结构可以为功能化小分子和颗粒提供一个适宜的、稳定的固化环境。联合这两种类型的纳米结构材料，例如将量子点掺入介孔玻璃的纳米孔道中，可以获得更多具有优异特性的纳米复合物。其中，具有超连续宽带和多色发光的量子点固化材料体系在电信通讯、微电子和太阳能电池领域有着广泛的应用前景。 我们设计了一个简单的浸渍方法成功实现了PbS量子点在溶胶凝胶介孔AlPO4玻璃块体中的掺杂。利用透射电子显微镜和深度测试的X射线光电子能谱验证了量子点在介孔AlPO4玻璃中的成功掺杂。通过调节溶液量子点的尺寸大小和玻璃介孔的平均孔径，获得了发光可调谐的PbS-AlPO4复合玻璃。通过设计不同的浸渍流程，我们成功制备了超连续宽带和多色发光的量子点-介孔玻璃。不仅如此，比较复合玻璃在180天之内的光谱变化情况，我们发现在介孔AlPO4玻璃中固化的PbS量子点与其他基体固化的PbS量子点相比有着更好的发光稳定性。 采用简单有效的实验手段，我们制备了基于AlPO4多孔膜的量子点复合膜体系。采用逐层组装旋涂的方法，将不同尺寸的PbS量子点沉积于AlPO4多孔膜上，我们获得了光谱可调谐的、多色输出的发光薄膜材料。利用原子力显微镜和扫描电子显微镜观察量子点复合膜的表面形貌，证明了量子点在AlPO4多孔膜上的沉积均匀而且紧密。此外，由于AlPO4多孔膜表面多孔结构的吸附和限域作用，沉积于AlPO4多孔膜上PbS量子点的发光稳定性与没有基质的量子点相比得到了明显的改善。我们发现，PbS量子点沉积于AlPO4多孔膜上之后，其发光光谱相对于液相量子点发生了红移。同时，将不同尺寸的量子点同时沉积，在不同尺寸量子点之间出现了能量传递现象。以上现象都表明了密堆积量子点薄膜的成功形成。 采用溶胶凝胶法在磷酸铝玻璃体系中合成了一系列的不同组分的PbxAlPO4、CdxAlPO4和ZnxAlPO4玻璃。这一类玻璃与介孔AlPO4类似具有高的比表面积和1~20 nm左右的多孔结构。以这些介孔玻璃为纳米反应器，利用其孔隙的空间限域作用，使用硫化氢、硫化钠为S源，调节不同的实验参数，在玻璃基体中原位生长得到了近红外波段发光的PbS量子点和可见波段发光的CdS、ZnS量子点。在此基础上，通过调节金属离子的掺杂浓度和介孔玻璃的孔径分布，获得了发光可调谐的量子点复合玻璃。Semiconductor quantum dots (QDs) and Mesoporous glasses are two typical classes of nanostructured materials. QDs were under intense studies on their distinct size-tunable optical properties and the quantum confinement effect. The structure of nanopores in mesoporous glass provides a stable and accessible surface for immobilizing various functional small particles and molecules. Combining these two types of nanostructures by incorporating QDs into nanopores could acquire novel nanocomposites. Broadly tunable and multi-emission quantum dot-solid systems have drawn great attention to the applications of telecommunication, microelectronics and solar cells. We designed a facile approach to fabricate high stable and controllable luminescent nanocomposites by confining PbS QDs in sol gel mesoporous AlPO4 monolithic glasses. The transmission electron microscopy images combined with X-ray photoelectron spectra in different depth of PbS-AlPO4 nanocomposites revealed the successful solidification of QDs in mesoporous structure of glasses. The tunable and controllable luminescence of PbS-AlPO4 nanocomposites was found dependent on the size of PbS QDs in solution and pore size of glasses. We showed that the broadband and bimodal emission of PbS QDs were tailored by designing different composited strategies on the incorporation of QDs in AlPO4 mesoporous glasses. The stability of PbS-AlPO4 nanocomposites was investigated by emission spectra after several to 180 days, and signifies a high stability compared with other regular PbS-solid materials. We proposed a simple and practical method for creation of QD-systems in porous AlPO4 glass film matrix. Tunable and bimodal luminescent films in near infrared were achieved by spin-coating based on a layer by layer assembly method with PbS QDs of different sizes. Atomic force microscopy and scanning electron microscopy revealed the successful deposition and homogeneous surface morphology of QD-AlPO4 glass films. Furthermore, as a result of adsorption and confinement from pores of AlPO4 substrate, the photo stability of QD-AlPO4 glass films was dramatically improved. The red-shift of QD photoluminescence spectra after depositing onto the matrix and energy transfer between QDs of different sizes indicated the formation of close-packed QD solid systems. Mesoporous PbxAlPO4, CdxAlPO4 and ZnxAlPO4 glasses with different doping concentration were prepared via the sol-gel route. These amorphous glasses exhibits an attractive mesoporous structure with pore width of 1~20 nm. They can be used as nano-reactors based on the spatial confinement effect. PbS QDs emitting in near infrared and CdS QDs, ZnS QDs emitting in visible range were in-situ grown on the surface and in the nanopores. What’s more, tunable luminescent QDs-glasses were achieved and dependent on the doping concentration and pore size of glasses