多孔铝镶嵌复合材料的光学性质研究

【作者】 董艳锋；

【导师】 李清山；

【作者基本信息】 曲阜师范大学 ， 物理电子学， 2002， 硕士

【摘要】 用电化学方法制备的多孔阳极氧化铝（简称多孔铝）是一种典型的自组织材料，长期以来一直受到国际科研组织的关注。目前人们主要将它作为模板或宿主，生长量子线、量子点等其它纳米材料。 本论文利用多孔铝非常高的孔隙率和纳米列阵结构，将有机发光材料8-羟基喹啉铝（Alq₃）和金属Cu分别填入多孔铝的孔中，研究了其光学性质。 第一章是多孔铝概述部分。主要讲述了多孔铝的形态结构、形成机理、制备过程以及制备条件（如氧化电压，氧化时间，电解液浓度、温度等）对多孔铝的影响，最后展望了多孔铝广泛的应用前景。 第二章论述了多孔铝镶嵌有机发光材料的光学性质，主要研究了复合镶嵌膜的荧光光谱。研究发现，其荧光光谱与Alq₃在乙醇溶液中的光谱相似，呈现单分子的发光特征，并且光谱线形更加对称。另外，我们还做了一系列实验考察了制备条件对有机镶嵌膜光致发光的影响，发现光谱与多孔铝中嵌入Alq₃分子的数量及聚集程度有关。当嵌入分子数量较多、聚集程度较大时，发光增强，光谱峰位发生红移，但聚集程度太大时，易发生荧光猝灭现象。数量较多时，Alq₃分子大多以范德瓦尔斯力结合，聚体较少，峰位移动幅度不大。另外，多孔铝的孔状结构，对有机分子有极强的吸附作用，使有机小分子大多以单体形式存在，致使Alq₃在多孔铝中发光峰位在490nm左右，比其在固态粉末状态蓝移了许多。实验中，Alq₃在多孔铝的孔中，基本上与周围的空气，水汽隔离开，所以光学性质稳定。实验结果表明，Alq₃在多孔铝中有较好的发光性质，多孔介质有机镶嵌膜有可能成为进一步发展Alq₃在电致发光器件方面应用的一条新途径。 第三章研究了含金属Cu纳米列阵多孔铝的偏振特性。将金属Cu用电镀方法填入多孔铝的孔中，形成金属Cu纳米列阵。由于金属柱相 摘 块 第2 页 互平行，入射光波的电场沿金属柱方向的分量驱动电子作功，该分量 被强烈地吸收，而垂直金属柱方向的分量基本不对电子作功，能够通 过，困此通过薄膜的透射光就成为偏振先。实验发现，镀铜多孔铝确 实像线栅偏振器一样表现出偏振性质。镀铜后的多孔铝在波长为1．SPm 时有较高的透射率和较大的消光比。把镀铜前后氧化铝的偏振特性相 比较，发现电镀后金属柱的增多使得镀铜后多孔铝的偏振度明显提高。 实验中还发现，镀铂多孔铝的偏振特性与阳极氧化和电镀条件有关。 随着电流密度的增大，金属柱增多，光学损失增大，透射率降低，而 偏振度增大。但是当电流密度增加到某一数值时，孔中的焦耳热不能 及时散发出去，将导致金属柱的有序度被破坏，所以偏振度降低。镀 铜多孔铝偏振器制作简单，体积微小，在光电通信领域有着非常广泛 的应用前景。更多还原

【Abstract】 In recent years, there has been increasing interest in the fabrication of ordered fine structures using naturally occurring self-ordered structures because of their potential utilization in the development of several kinds of micromechanical, electronic and optoelectronic devices. Alumina films anodized in acid solutions contain column pores arranged parallel to one another. The size and spacing of the pores are almost uniform all over the film. The radius of the pores can be controlled in the range of 1.5 to 500 nm by changing the anodization condition such as the type of acid solution, temperature, anodizing voltage et al. The material has recently attracted increasing attention as a host by-introducing a guest.In this dissertation, organic emitting materials(8-hyrdoxyquinoline) aluminum(Alq3) and the metal Cu were embedded in porous alumina respectively. The optical properties of the compound films were studied.In Chapter One, the morphology, mechanism and process of formation, influences of the preparation condition on the anodic alumina, and the development prospects are discussed.In Chapter Two, the photoluminescence(PL) of the films embedded Alqs was discussed. The results showed that the PL of the compound film was similar to that in liquid, but the symmetry of the compound film was better. The peak exhibited blue shift, but interestingly, the full width at half maximum was larger. Then a series of embedded samples were prepared to research further. It was indicated that the PL of the embedded films was correlative with the quantity and the degree of conglomeration of the moleculars of Alqs embedded in the porous alumina. With the number increasing, the peak of PL exhibited red shift, and the intensity enhanced; but the intensity decreased unexpectedly when the conglomeration was too large. As most of the moleculars of Alqa existed in Van der Waals bindingwhen the number was high, the range of PL shifted a little. The peak of the PL of the embedded film was blue shirt compared with Alq3 in the solid powder, because of the high porosity of anodic film. The experimental results suggested that the porous alumina may be a better encapsulated media for Alqa, and this may make a new way for Alqs in application in electroluminescence.In Chapter Three, the polarization performance of the films with metal Cu columns was investigated. The columns electroplated into the cylindrical micropores arranged in parallel would exibit high optical anisotropy. It was found that the films embedded did work like a good wire grid polarizer. At the wavelength of 1.5 (am, the films embedded manifested higher transmissivity and better extinction ratio. Compared with the anodic alumina, the extinction ratio of the films with Cu columns was higher. The dependence of the polarization properties on anodization and electroplating conditions was also studied. The polarization property was increasing with the current density growing, because of the growth of metallic columns. But the trend was stopped when the current density was too high to make the Joule heat exhale as quickly as possible and resulted in the irregularity of the columns. The simple microprocessing techniques, the low cost and the small bulk make the film embedded Cu extensive prospects in optical telecommunication.更多还原