Sub-molecular structural relaxation at a physisorbed interface with monolayer organic single-crystal semiconductors
Sub-molecular structural relaxation at a physisorbed interface with monolayer organic single-crystal semiconductors
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DOI：
10.1038/s42005-020-0285-7
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发表时间：
2020-01
影响因子：
5.5
通讯作者：
Akifumi Yamamura;H. Fujii;H. Ogasawara;D. Nordlund;O. Takahashi;Yuutaro Kishi;H. Ishii;N. Kobayashi-N.
中科院分区：
文献类型：
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作者：
Akifumi Yamamura;H. Fujii;H. Ogasawara;D. Nordlund;O. Takahashi;Yuutaro Kishi;H. Ishii;N. Kobayashi-N.
将分子排列成高度对称的拓扑晶体结构被认为是使分子晶体中的电子性质功能化的最佳途径，其中组成分子的形状被假定为刚性。在这里，与之形成鲜明对比的是，我们证明了单层有机晶体中的分子在靠近衬底时可以经历显著的形变，这反映在电子密度分布的不对称性上。X射线反射率和X射线吸收光谱结合密度泛函理论计算表明，高度平坦化的π芯形变成弯曲形状，而体晶格参数保持不变。分子的形状变化在双层单晶中得到了很好的抑制，这导致双层晶体的迁移率增加了40%。我们在单层单晶中发现了独特的亚分子尺度的形状变化，这为通过纳米级物理吸附实现电学性质功能化提供了可能性。
Arranging molecules into highly symmetric, topological crystal structures has been recognized as the best approach to functionalize electronic properties in molecular crystals, where the constituent molecules have been assumed to be rigid in shape. Here, in striking contrast, we demonstrate that the molecules in a monolayer organic crystal can undergo a significant deformation in proximity to the substrate, which is reflected by an asymmetry in the electron density profile. X-ray reflectivity and X-ray absorption spectroscopies in conjunction with density-functional theory calculations reveal that the highly planarizedπ-core are deformed into a bent shape, while the bulk lattice parameters are maintained. The molecular shape change is found to be perfectly suppressed in a bilayer single crystal, which leads to a 40% increase in mobility in the bilayer crystal. Our finding of a unique, sub-molecular scale shape change in monolayer single crystals can offer possibilities for functionalizing electrical properties via nano-scale physisorption.