New design strategies for tuning electrode properties by SAMs

化学锚定自组装单分子膜（SAMs）在有机和分子电子学领域起着至关重要的作用。它们通常被用来改变界面的电子性质或作为纳米级器件的有源元件。在这种情况下，特别感兴趣的是结合到金属电极的SAM，当在其尾部用极性单元取代时，改变电荷载流子注入。在这种情况下的复杂性是，由于偶极-偶极排斥，在这样的层中形成SAM成为一个挑战。为了克服这个问题，我们将设计新型的SAM，其中通过分布偶极单元来减少偶极-偶极排斥或通过在SAM形成分子之间诱导氢键来稳定层。为了实现后一种方法，我们将研究与靛蓝或喹吖啶酮等染料分子相关的系统。对于键合到金属表面的这种分子，例如，通过硫醇盐锚，我们期待新的性质，如前所未有的量级的功函数修改以及由层内化学和静电耦合引起的独特的电子特性。为了实现计划研究的全部潜力，我们将联合收割机结合六个研究小组的理想互补的专业知识：Terfort（法兰克福大学）及其同事将合成所需的分子，这些分子要么具有分布的偶极矩，要么具有形成染料的氢键网络。M. Zharnikov（海德堡大学）和他的小组将设计优化策略，在金属衬底上生长这种自组装膜，表征其结构电子特性，并与R。Resel（TU格拉兹）将研究有机半导体在修饰电极上的生长。E. Zojer（TU格拉兹）和他的同事将使用原子模型来确定最有前途的分子结构，指导合成工作，并解释实验观察。K. Zojer（TU格拉兹）和她的学生将建模，SAM改性电极预计将如何改变电荷载流子注入到有机薄膜晶体管中，特别注意非均匀性在薄膜电子特性中的作用。最后，B会将本计画所设计的自组装模组应用于实际的元件结构中。Stadlober和她的团队（Joanneum Research）。所有上述研究工作将密切联系在密切的反馈回路中，并通过几个层次的信息交流加以保证。通过如此多不同方法的紧密集成，我们期望对所研究系统的电子和结构特性有前所未有的了解。这有可能显著影响人们对自组装单层的看法，并促进其在实际有机电子器件中的应用。此外，多学科的方法和刺激的研究环境将极大地拓宽所有参与科学家的科学视角，特别是学生。

Chemically anchored self-assembled monolayers (SAMs) play a crucial role in the area of organic and molecular electronics. They are usually used to modify the electronic properties of interfaces or to act as the active elements of nano-scale devices. Of particular interest in this context are SAMs bonded to metal-electrodes, which, when substituted with polar units at their tails, modify charge-carrier injection. A complication in that context is that due to the dipole-dipole repulsion, SAM-formation in such layers becomes a challenge. To overcome that problem, we will design novel types of SAMs, where the layers are stabilized either by reducing dipole-dipole repulsion via distributing the dipolar units or by inducing hydrogen-bonds between the SAM-forming molecules. To realize the latter approach, we will study systems related to dye molecules like indigo or quinacridone. For such molecules bonded to metal surfaces, e.g., via thiolate anchors, we expect novel properties like work-function modifications of unprecedented magnitude as well as peculiar electronic characteristics arising from the intra-layer chemical and electrostatic coupling. To realize the full potential of the planned research, we will combine the ideally complementary expertise of six research groups: A. Terfort (Univ. Frankfurt) and co-workers will synthesize the required molecules either with distributed dipole moments or the H-bond network forming dyes. M. Zharnikov (Univ. Heidelberg) and his group will devise optimized strategies for growing such SAMs on metal substrates, characterize their structural electronic properties, and together with the group of R. Resel (TU Graz) will study the growth of organic semiconductors on modified electrodes. E. Zojer (TU Graz) and his co-workers will use atomistic modeling to identify the most promising molecular structures guiding the synthetic efforts and to explain experimental observations. K. Zojer (TU Graz) and her students will model, how SAM-modified electrodes are expected to change the charge carrier injection into organic thin-film transistors paying special attention to the role of inhomogenieties in the films electronic properties. Finally, the SAMs designed in this project will be applied in actual device-structures by B. Stadlober and her group (Joanneum Research). All above mentioned research efforts will be intimately linked in close feedback-loops guaranteed by several levels of information exchange. From the tight integration of so many different approaches we expect an unprecedented level of understanding of the electronic and structural properties of the studied systems. This has the potential to significantly impact the way one thinks about self-assembled monolayers and to promote their use in actual organic electronic devices. Moreover, the multi-disciplinary approach and the stimulating research environment will hugely broaden the scientific perspectives of all involved scientists, in particular the students.