【作者】 周树兰；

【导师】 赵显；

【作者基本信息】 山东大学 ， 材料学， 2006， 硕士

【摘要】 双光子吸收材料在光电、医学、生物等领域发挥了非常重要的作用。具有大的双光子吸收截面的有机材料由于其在双光子上转换激光、光限幅、三维光存储和双光子光动力学治疗等方面的潜在应用前景引起了广泛关注。双光子吸收应用的一个关键的前提是具有大的双光子吸收截面的有机材料的合成。由于影响有机分子双光子吸收性质的因素较多，因此从理论上研究分子的结构—双光子吸收性质关系对于具有大的双光子吸收截面的有机材料的实验合成具有重要意义。 本论文以二苯乙烯、二噻吩并噻吩和吡啶类分子为基础，采用ZINDO／SOS方法计算分子的双光子吸收截面，从理论上系统研究了共轭体系的长度、取代基的推拉电子能力、π共轭桥的类型三个因素对分子的双光子吸收性质的影响，并研究了具有多分支结构的分子的双光子吸收性质。对多分支分子，分别从分支的数量、分支的结构和耦合中心三个方面研究了分子的结构—双光子吸收性质关系。通过研究得到了以下结论： 1．分子的双光子吸收截面与共轭体系的长度在一定范围内成线性关系，但是分子的双光子吸收截面随体系共轭长度的增大具有饱和性。 2．推拉电子能力大的取代基有利于增大分子的双光子吸收截面，但双光子吸收截面的改变与分子的共轭桥的类型有关。给体取代和受体取代会增大分子在不同波长范围内的双光子吸收，侧基取代可使分子的双光子吸收大大红移，因此，通过改变分子的取代基可以得到在预期波长具有较大双光子吸收截面的分子。 3．π共轭桥对分子的双光子吸收性质具有决定性的影响。离域性强的共轭桥有利于分子的双光子吸收截面的增大。本文研究表明二噻吩并噻吩、二乙烯、二乙炔和二偶氮两端连接二苯乙烯吡啶构成的分子具有较好的双光子吸收性质。 4．多分支分子的分支之间存在耦合作用可使分子的双光子吸收截面显著增大，但是并不是所有的多分支分子都具有比单支分子大很多的双光子吸收截面，这与分支数、分支结构和耦合中心有关。合理的分支数、离域性强的分支和耦更多还原

【Abstract】 Two-photon-absorption materials are playing an important role in many fields such as photoelectricity, medical treatment, biology and so on. Organic materials with large two-photon absorption cross section have attracted considerable attention for their potential applications such as two-photon upconverted lasing, two-photon optical power limiting, three-dimensional optical storage and photodynamic therapy. The development of two-photon technology relies much on the success of synthesis of new molecules with very large TPA cross sections at desirable wavelengths. Many factors can affect the two-photon absorption properties in organic materials. So it is important to investigate the structure and the two-photon absorption property relationship for organic materials.In this thesis, the effects of the conjugated length, the strength of subsitituents and the type of π conjugated bridge on the two-photon absorption properties were systematically studied by the ZINDO/SOS (Sum-Over-States) method. And in order to study the structure—property relationship for the muti-branched molecules , the influences of the number of branches, the structure of the branches and the coupled center on the muti-branched molecules were systematically investigated as well. All the investigated molecules were designed based on the stilbene, dithienothiophene and pyridinium chromophores. In this thesis, the following conclusions can be deduced:1. The two-photon absorption cross section of organic materials depends almost linearly on the conjugation length but the two-photon absorption cross section for the molecules beyond some chain length would be saturated.2. Increasing the strength of donor or acceptor moieties attached symmetrically or asymmetrically to a conjugated linker can result in the enhancement of the TPA cross section. However the enhancement depends on the type of the π conjugated bridge. The donor and acceptor can enhance the TPA cross section at different wavelength更多还原