Max Planck Institute for Solid State Research , Heisenbergstrasse 1, 70569 Stuttgart, Germany.
J Am Chem Soc. 2013 Nov 6;135(44):16585-94. doi: 10.1021/ja408355p. Epub 2013 Oct 3.
Organic oligomers and polymers with extended π-conjugation are the fundamental building blocks of organic electronic devices. Novel routes are being explored to create tailor-made organic materials, and recent progress in organic chemistry and surface chemistry has led to the synthesis of planar 2D polymers. Here we show how extending π-conjugation in the second dimension leads to novel materials with HOMO-LUMO gaps smaller than in 1D polymers built from the same parent molecular repeat unit. Density functional theory calculations on experimentally realized 2D polymers grant insight into HOMO-LUMO gap contraction with increasing oligomer size and show fundamental differences between 1D and 2D "band gap engineering". We discuss how the effects of cross-conjugation and dihedral twists affect the electronic gaps.
具有扩展π共轭的有机低聚物和聚合物是有机电子器件的基本构建块。人们正在探索新的途径来创造定制的有机材料，而有机化学和表面化学的最新进展导致了平面二维聚合物的合成。在这里，我们展示了如何在二维空间中扩展π共轭，从而得到具有比由相同母体分子重复单元构建的一维聚合物更小的 HOMO-LUMO 能隙的新型材料。对实验实现的二维聚合物进行的密度泛函理论计算深入了解了随着低聚物尺寸的增加 HOMO-LUMO 能隙的收缩，并显示了一维和二维“带隙工程”之间的根本区别。我们讨论了交叉共轭和二面角扭曲的影响如何影响电子间隙。
