A molecular-scale portrait of domain imaging in organic surfaces
Progress in the general understanding of structure-property relationships in organic semiconductors requires experimental tools capable of imaging structural details, as molecular packing or domain attributes, featuring ultra-thin films. A rarely employed operation mode of scanning force microscopy,...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2017 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/152673 |
| Acceso en línea: | http://hdl.handle.net/10261/152673 |
| Access Level: | acceso abierto |
| Palabra clave: | Organic semiconductors Friction anisotropy AFM TSM Simulation Stick-slip |
| Sumario: | Progress in the general understanding of structure-property relationships in organic semiconductors requires experimental tools capable of imaging structural details, as molecular packing or domain attributes, featuring ultra-thin films. A rarely employed operation mode of scanning force microscopy, related to friction force microscopy (FFM) and known as transverse shear microscopy (TSM), has demonstrated the ability to reveal crystalline aspects linked to the surface symmetry of organic surfaces with nanometer resolution. In spite of those promising results, numerous questions remain about the physical origin of the TSM imaging mechanism. Taking as benchmark a PTCDI-C8 sub-monolayer, we demonstrate experimentally and theoretically that such mechanism is the same atomic scale stick-slip ruling FFM leading to the angular dependence of both signals. Lattice-resolved images acquired on top of differently oriented PTCDI-C8 molecular domains are crucial to permit azimuthal sampling, without the need of sample rotation. The simulations reveal that, though the surface crystallography is the direct cause of the FFM and TSM signals, the manifestation of anisotropy will largely depend on the amplitude of the surface potential corrugation as well as on temperature and the material itself. This work provides a novel nanoscale strategy for the quantitative analysis of organic thin films based on their nanotribological response. |
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