Designing molecular organic semiconductors with distinct frontier orbitals is key for the development of devices with desirable properties. Generating defined organic nanostructures with atomic precision can be accomplished by on-surface synthesis. We use this “dry” chemistry to introduce topological variations in a conjugated poly(para-phenylene) chain in the form of meta-junctions. As evidenced by STM and LEED, we produce a macroscopically ordered, monolayer thin zigzag chain film on a vicinal silver crystal. These cross-conjugated nanostructures are expected to display altered electronic properties, which are now unraveled by highly complementary experimental techniques (ARPES and STS) and theoretical calculations (DFT and EPWE). We find that meta-junctions dominate the weakly dispersive band structure, while the band gap is tunable by altering the linear segment’s length. These periodic topology effects induce significant loss of the electronic coupling between neighboring linear segments leading to partial electron confinement in the form of weakly coupled quantum dots. Such periodic quantum interference effects determine the overall semiconducting character and functionality of the chains.

中文翻译：

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电子结构可调性通过定期元-配体间距一维有机半导体

设计具有不同前沿轨道的分子有机半导体是开发具有所需性能的器件的关键。可以通过表面合成来以原子精度生成定义的有机纳米结构。我们使用这种“干”化学，以在共轭聚（引入拓扑变化对位亚苯基）链中的形式的元-junctions。正如STM和LEED所证明的那样，我们在邻近的银晶体上生产了宏观有序的单层之字形薄链膜。这些交叉共轭的纳米结构有望显示出改变的电子特性，而高度互补的实验技术（ARPES和STS）和理论计算（DFT和EPWE）现已揭示了这些电子特性。我们发现那个元-结在弱色散带结构中占主导地位，而带隙可通过更改线性段的长度来调整。这些周期性的拓扑效应导致相邻线性段之间电子耦合的明显损失，从而导致弱耦合量子点形式的部分电子约束。这种周期性的量子干扰效应决定了链的整体半导体特性和功能。