New design strategies for tuning electrode properties by SAMs

化学锚定自组装单层膜（SAMs）在有机和分子电子学领域发挥着至关重要的作用。它们通常用于修饰界面的电子特性或作为纳米级器件的有源元件。在这种情况下，特别令人感兴趣的是与金属电极结合的sam，当在其尾部用极性单元取代时，可以改变载流子注入。在这种情况下，一个复杂的问题是，由于偶极子-偶极子斥力，在这种层中形成sam成为一个挑战。为了克服这个问题，我们将设计新型的sam，通过分布偶极单元或通过在sam形成分子之间诱导氢键来减少偶极-偶极排斥来稳定层。为了实现后一种方法，我们将研究与染料分子相关的系统，如靛蓝或喹吖酮。对于这样的分子，例如，通过硫酸盐锚定，结合到金属表面，我们期望新的性质，如空前量级的功函数修改，以及由层内化学和静电耦合产生的特殊电子特性。为了充分发挥计划研究的潜力，我们将结合六个研究小组的理想互补专业知识：A. Terfort（法兰克福大学）和同事将用分布式偶极矩或氢键网络形成染料合成所需的分子。M. Zharnikov（海德堡大学）和他的团队将设计出在金属衬底上生长这种SAMs的优化策略，表征其结构电子特性，并与R. Resel（格拉茨工业大学）团队一起研究有机半导体在修饰电极上的生长。E. Zojer （TU Graz）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结果。K. Zojer （TU Graz）和她的学生将模拟sam修饰电极如何改变有机薄膜晶体管中的载流子注入，并特别关注薄膜电子特性中的不均匀性。最后，本项目设计的sam将由B. Stadlober和她的团队（Joanneum Research）应用于实际的器件结构中。上述所有研究工作将在若干级别的信息交换保证的密切反馈循环中密切联系起来。从许多不同方法的紧密集成中，我们期望对所研究系统的电子和结构特性的理解达到前所未有的水平。这有可能显著影响人们对自组装单层膜的看法，并促进其在实际有机电子设备中的应用。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，特别是学生的科学视野。

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.