【作者】 孙淼；

【导师】 张景萍；

【作者基本信息】 东北师范大学 ， 材料物理与化学， 2008， 硕士

【摘要】 螺双芴衍生物在OLED中有广泛的实际应用价值。与螺双芴相比,硅中心螺双芴结构的膜形态具有较好的稳定性和新颖独特的发光性能,表现出良好的应用前景。了解化合物电子激发态的性质与化学及几何结构的关系对于设计新型电子学材料和调节其光/电性质具有重要意义。人们对硅中心螺双芴衍生物的发光性质在实验上开展了大量研究工作,但缺少理论上的充分支持。本研究组曾经以硅中心螺双芴衍生物为模型化合物,选择适合该体系的计算方法和基组,合理地解释了已有的实验事实。在此基础上,本论文采用所选择的计算方法,设计了多种新型的硅中心螺双芴发光材料作为蓝光材料。本文以硅中心螺双芴为母体化合物,共设计了三类新型硅中心螺双芴衍生物蓝光材料,首先将N杂原子引入母体化合物骨架,设计“CH”/N取代的系列硅中心螺双芴衍生物,同时研究其相应–Ph与–t–Bu取代衍生物及二聚物的性质;其次将系列单和多–NO2、–CN、–NH2和–OCH3取代基分别引入母体化合物,设计H/R(R =–NO2、–CN、–NH2和–OCH3)取代的硅中心螺双芴衍生物;将具有推拉电子效应(push-pull)的双取代基引入母体化合物,形成具有push-pull效应的取代硅中心螺双芴衍生物。采用HF/6-31G*方法优化设计衍生物的基态几何结构,用B3LYP/6-31G*方法计算衍生物的电子性质;并用CIS/6-31G*方法优化它们第一激发态的几何结构;采用TD-B3LYP/6-31G*方法计算吸收与发射光谱。计算结果表明,设计的衍生物的基态和激发态结构分别与其母体的基态和激发态结构相比,没有明显的变化。–NH2和–NO2二取代的推拉电子体系,双–NH2取代以及双–NO2取代衍生物的发射光谱有明显的红移,它们相对于分子母体的红移波长分别为56 nm,96 nm和61 nm,可以作为蓝光材料。同时“CH”/N取代的衍生物的吸收和发射波长与母体相比没有明显的变化,但是在这些衍生物中存在着明显的电荷转移性质。“CH”/N取代的硅中心螺双芴衍生物可以看作是,在不改变发光颜色的前提下,能进行有效电荷转移的新型电致发光材料。根据理论计算结果,在设计的衍生物中引入苯环、加入push-pull效应或形成低聚物,均可以使吸收和发射光谱的振子强度提高,改善它们的光学性质。通过前线分子轨道的分布,以及HOMO–LUMO能隙,我们更深入地研究和解释了其光学性质的变化,为新材料的设计提供有效的理论依据。更多还原

【Abstract】 Spirobifluorene derivatives have many kinds of applications such as in OLEDs. Compared with spirobifluorene, spirosilabifluorene may have an improved morphological stability in films. Identifying the relation between electronic excitation properties and the chemical as well as the geometrical structures is the key tool for a directed design of new electronic compounds and tuning of their photo electronic properties. Although this task can be addressed from the theoretical standpoint, a few computational works relating to this type of materials can be found in the literature. In this contribution, we design new photoluminescence materials based on the selected approaches for spirosilabifluorene based materials.To better understand the substitutional effect, the“CH”/N, H/R (R =–NO2,–CN,–NH2 and–OCH3) substituted spirosilabifluorene derivatives are investigated. Equilibrium ground state geometry configurations and their relevant electronic properties of these derivatives are calculated by HF/6-31G* method. Their first excited state geometries are investigated using CIS/6-31G* method. The optical properties for designed molecules are investigated by TD-B3LYP/6-31G* approach. According to our results, the structures do not show any appreciable change. In comparison with the parent molecule, significant red-shift is predicted for the emission spectra of the di-substituted derivatives with–NH2 (96nm),–OCH3 (61nm) and the push-pull (containing both–NH2 and–NO2) derivative (56nm). No apparent change is however predicted for the absorption/emission wavelengths within the“CH”/N substituted derivatives, an efficient charge transfer being revealed. These properties may make these derivatives potential candidates for blue or violet-blue emitting materials. Furthermore, we find that the performance and the optical properties of these derivatives can be improved by adding aryl group, push-pull substitutents or oligomerization. The optical properties for the investigated derivatives can be explained by the distribution pattern of HOMO and LUMO and the energy gap.更多还原