Chhikara Manisha, Bratina Gvido, Pavlica Egon
Laboratory of Organic Matter Physics, University of Nova Gorica, Vipavska Cesta 13, SI-5000 Nova Gorica, Slovenia.
ACS Omega. 2023 Jul 24;8(30):27534-27542. doi: 10.1021/acsomega.3c03174. eCollection 2023 Aug 1.
Using atomic force microscopy, we probed the growth of pentacene molecules on graphene that was fabricated by chemical vapor deposition and transferred onto 300 nm-thick SiO substrates. The topography of such graphene has two important properties. First, its surface is comprised of folds that have different orientations, and second, it has several multilayer-graphene regions distributed over the monolayer-graphene surface. On such folded graphene features, we vacuum evaporated pentacene and observed three-dimensional islands with an average height of ∼15 nm. They are oriented either parallel or perpendicular to the folds, and they are also predominantly oriented along the symmetry axes of graphene. Orientation of pentacene islands on graphene evaporated at room temperature has a wide distribution. On the contrary, most of the pentacene islands evaporated at 60 °C are oriented at 30° with respect to the fold direction. We observed that the folds act as a potential barrier for the surface transport of pentacene molecules. In addition, we interpret the 3D growth of pentacene islands on graphene in terms of reduced polar components of the surface energy on graphene investigated with contact angle measurements.
我们使用原子力显微镜研究了并五苯分子在通过化学气相沉积制备并转移到300纳米厚二氧化硅衬底上的石墨烯上的生长情况。这种石墨烯的形貌有两个重要特性。其一，其表面由具有不同取向的褶皱组成；其二，在单层石墨烯表面分布着多个多层石墨烯区域。在这种有褶皱的石墨烯特征上，我们真空蒸发并五苯，观察到平均高度约为15纳米的三维岛状物。它们要么平行于褶皱，要么垂直于褶皱，并且主要沿着石墨烯的对称轴取向。在室温下蒸发的并五苯岛状物在石墨烯上的取向分布很广。相反，在60°C下蒸发的大多数并五苯岛状物相对于褶皱方向成30°角取向。我们观察到褶皱对并五苯分子的表面传输起到了势垒作用。此外，我们通过接触角测量研究了石墨烯表面能的极性分量降低，以此来解释并五苯岛状物在石墨烯上的三维生长情况。
