Preparation and photoluminescence of SiO2-CdTe multilayer film by layer-by-layer self-assembly
Preparation and photoluminescence of SiO2-CdTe multilayer film by layer-by-layer self-assembly
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DOI：
10.1088/1742-6596/152/1/012009
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发表时间：
2009-03
期刊：
影响因子：
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通讯作者：
Ping Yang;N. Murase
中科院分区：
文献类型：
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作者：
Ping Yang;N. Murase
研究了由功能SiO_2层和发光量子点(QDS)层组成的层层自组装薄膜的制备工艺。将经过表面处理的平板先后浸入三种不同的溶液中：表面活性剂(硫代乙醇酸，TGA)、胶体量子点和功能硅烷。由于第一种溶液中的游离TGA分子成为两种膜之间的连接物，所以第一种溶液的条件(TGA和Cd~(2+)离子浓度和pH)影响薄膜的性能。在最佳条件下，量子点在高浓度(0.01M)下以紧密堆积的方式分散，没有团聚。这导致光致发光(PL)光谱变窄，并由于发射的重新吸收而导致峰值波长红移。用这种方法制备的具有10个双层(约50 nm厚)的薄膜的发光效率为25%。当它们的厚度相同时，这种高效率加上高浓度导致的亮度比商业荧光粉高得多。然而，当第一种溶液中存在过量的TGA分子时，由于量子点的团聚，薄膜具有较高的浓度(0.02M)和较低的发光效率。
Preparation parameters of layer-by-layer self-assembled films consisting of functional SiO2 layers and emitting CdTe quantum dots (QDs) layers were investigated. A surface-treated plate was successively dipped into three different solutions: surfactant (thioglycolic acid, TGA), colloidal QDs, and functional silicon alkoxide. Since the free TGA molecules in the first solution became linkers between the two kinds of layers, the condition of the first solution (TGA and Cd2+ ion concentrations and pH) affected the properties of the film. Under optimal conditions, the QDs were dispersed at a high concentration (0.01 M) in a closely packed manner without agglomeration. This resulted in a narrowing of the photoluminescence (PL) spectrum and a red shift of the peak wavelength due to reabsorption of the emission. The PL efficiency of films thus prepared with ten double layers (ca. ~50 nm thick) was 25%. This high efficiency together with the high concentration resulted in a brightness much higher than that of a commercial phosphor when their thickness was same. However, when there were excess free TGA molecules in the first solution, the film had a higher concentration (0.02 M) and lower PL efficiency due to agglomeration of the QDs.