Rao Vaishnavi J, Qi Haoyuan, Berger Felix J, Grieger Sebastian, Kaiser Ute, Backes Claudia, Zaumseil Jana
Institute for Physical Chemistry, Universität Heidelberg, D-69120 Heidelberg, Germany.
Central Facility of Materials Science Electron Microscopy, Universität Ulm, 89081 Ulm, Germany.
ACS Nano. 2021 Dec 28;15(12):20466-20477. doi: 10.1021/acsnano.1c08965. Epub 2021 Nov 23.
Liquid phase exfoliation (LPE) is a popular method to create dispersions of two-dimensional nanosheets from layered inorganic van der Waals crystals. Here, it is applied to orthorhombic and triclinic single crystals of the organic semiconductor rubrene with only noncovalent interactions (mainly π-π) between the molecules. Distinct nanorods and nanobelts of rubrene are formed, stabilized against aggregation in aqueous sodium cholate solution, and isolated by liquid cascade centrifugation. Selected-area electron diffraction and Raman spectroscopy confirm the crystallinity of the rubrene nanorods and nanobelts while the optical properties (absorbance, photoluminescence) of the dispersions are similar to rubrene solutions due to their randomized orientations. The formation of these stable crystalline rubrene nanostructures with only a few molecular layers by LPE confirms that noncovalent interactions in molecular crystals can be strong enough to enable mechanical exfoliation similar to inorganic layered materials.
液相剥离（LPE）是一种从层状无机范德华晶体中制备二维纳米片分散体的常用方法。在此，该方法应用于有机半导体红荧烯的正交晶系和三斜晶系单晶，分子间仅存在非共价相互作用（主要是π-π相互作用）。形成了独特的红荧烯纳米棒和纳米带，它们在胆酸钠水溶液中稳定不聚集，并通过液体级联离心法分离出来。选区电子衍射和拉曼光谱证实了红荧烯纳米棒和纳米带的结晶性，而分散体的光学性质（吸光度、光致发光）由于其随机取向与红荧烯溶液相似。通过液相剥离法形成这些仅由少数分子层组成的稳定结晶红荧烯纳米结构，证实了分子晶体中的非共价相互作用可以足够强，从而实现类似于无机层状材料的机械剥离。
