Baranowski Daniel, Thaler Marco, Brandstetter Dominik, Windischbacher Andreas, Cojocariu Iulia, Mearini Simone, Chesnyak Valeria, Schio Luca, Floreano Luca, Gutiérrez Bolaños Carolina, Puschnig Peter, Patera Laerte L, Feyer Vitaliy, Schneider Claus M
Peter Grünberg Institute (PGI-6), Jülich Research Centre, 52428 Jülich, Germany.
Department of Physical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria.
ACS Nano. 2024 Jul 17;18(30):19618-27. doi: 10.1021/acsnano.4c04191.
Two-dimensional metal-organic frameworks (2D-MOFs) represent a category of atomically thin materials that combine the structural tunability of molecular systems with the crystalline structure characteristic of solids. The strong bonding between the organic linkers and transition metal centers is expected to result in delocalized electronic states. However, it remains largely unknown how the band structure in 2D-MOFs emerges through the coupling of electronic states in the building blocks. Here, we demonstrate the on-surface synthesis of a 2D-MOF exhibiting prominent π-conjugation. Through a combined experimental and theoretical approach, we provide direct evidence of band structure formation upon hierarchical self-assembly, going from metal-organic complexes to a conjugated two-dimensional framework. Additionally, we identify the robustly dispersive nature of the emerging hybrid states, irrespective of the metallic support type, highlighting the tunability of the band structure through charge transfer from the substrate. Our findings encourage the exploration of band-structure engineering in 2D-MOFs for potential applications in electronics and photonics.
二维金属有机框架材料（2D-MOFs）是一类原子级超薄材料，它将分子体系的结构可调控性与固体的晶体结构特征相结合。有机连接体与过渡金属中心之间的强键合有望产生离域电子态。然而，二维金属有机框架材料中的能带结构是如何通过构建单元中电子态的耦合而出现的，在很大程度上仍然未知。在此，我们展示了一种具有显著π共轭的二维金属有机框架材料的表面合成。通过实验与理论相结合的方法，我们提供了从金属有机配合物到共轭二维框架的分级自组装过程中能带结构形成的直接证据。此外，我们确定了新兴杂化态的强色散性质，而与金属支撑类型无关，突出了通过从衬底进行电荷转移来调节能带结构的能力。我们的研究结果鼓励在二维金属有机框架材料中探索能带结构工程，以用于电子学和光子学的潜在应用。
