Studies of Metal-Organic and Organic Charge-Transport for Plastic Opto-Electronics

本计划的目的是通过以下方式提高分子电荷传输剂的最新水平：i)加深对高迁移率材料中无序和重组能的相对重要性的认识；ii)开发高迁移率材料。这将通过使用具有或多或少非成键前线轨道的系统以及通过使用具有高度离域的前线轨道的系统来最小化重组能；通过使用具有向分子外围离域的扩散轨道的系统来最大化分子间电子耦合；通过使用能够比典型的有机电荷传输剂更各向同性重叠的物种以及通过使用柱状盘状液晶材料来最大化分子间的电子耦合。为了最小化重组能量，在保持原子核冻结的同时移动电子所需的能量，应该选择前线轨道几乎没有成键或反键特征的系统，或者它们被广泛地离域的系统。在这方面，我们将研究金属有机化合物中金属基轨道上电子的去除。为了最大限度地实现轨道重叠，将采取两种办法。首先，将研究具有比大多数有机电荷传输剂(通常包含基本平面核心，例如TPD中的联苯单元)更多的三维形状的有机金属和配位化合物(例如八面体、四面体)。通过这种方式，预计重叠不会依赖于玻璃介质中的取向因素；即最近邻分子之间的重叠总是好的。此外，这些材料很可能形成具有各向同性迁移率的各向同性玻璃，这将在一些设备中发挥作用。第二种方法包括检查材料，这些材料自组织成柱状盘状中间相，其中沿分子列的重叠被最大化。在进行这项研究的过程中，学生将接受跨学科的培训，包括合成和物理测量。

0309131MarderThe aim of this program is to improve the state-of-the-art of molecular charge-transport agents by: i) developing an understanding of the relative importance of disorder and reorganization energy in high-mobility materials and ii) developing high-mobility materials. This will be accomplished by minimizing reorganization energy by using systems with more-or-less non-bonding frontier orbitals, and by using systems with highly delocalized frontier orbitals; maximizing intermolecular electronic coupling by using systems with diffuse orbitals delocalized towards the periphery of the molecule, by using species capable of more isotropic overlap than typical organic charge-transport agents, and by using columnar discotic liquid-crystalline materials.To minimize reorganization energy, the energy required to move the electron whilst leaving nuclei frozen, systems should be selected in which the frontier orbitals have little bonding or anti-bonding character, or in which they are extensively delocalized. Removal of electrons from metal based orbital in organometallic compounds will be investigated in this regard. To maximize orbital overlap two approaches will be pursued. Firstly, organometallic and coordination compounds with rather more three-dimensional shapes (e.g. octahedral, tetrahedral) than most organic charge-transport agents (which often contain basically planar cores; e.g. the biphenyl unit in TPD) will be investigated. In this way, it is anticipated that the overlap will not be dependent upon orientational factors in glassy media; i.e. that overlap between nearest neighbor molecules will always be good. Moreover, these materials are likely to form isotropic glasses with isotropic mobilities, which will be useful in some devices. This second approach involves examination materials that self-organize into columnar discotic mesophases in which overlap along the column of molecules is maximized. In the process of performing this research students will receive an interdisciplinary training, working on both synthesis and physical measurements.