Transporte de carga en uniones moleculares no centro simétricas oro - molécula – grafeno.

Abstract

The current technology used in the construction of electronic components is the complementary metal–oxide–semiconductor (CMOS) technology. This technology is approaching the limits at which miniaturization is possible. Molecular electronics emerges as a viable alternative to CMOS technology. Molecular electronics is based on using one or several molecules anchored between electrodes in order to construct electronic components. Contemporary molecular electronics explores the use of non-metallic materials, such as graphene or molybdenum disulfide. The introduction of asymmetries in molecular junctions is also an interesting area of study. These asymmetries may arise from asymmetries in anchoring groups, asymmetries in the molecular backbone, or from the use of different materials for the electrodes. This work analyses the charge transport characteristics in the asymmetric junction gold – molecule- graphene. The molecule 4-4’ biphenyl dithiol was used, along with graphene obtained through electrochemical exfoliation and improved using the liquid cascade centrifugation) (LCC) technique. UV-Vis spectroscopy was used to identify graphene and to measure its concentration. Graphene electrodes were constructed using spray coating. Atomic force microscopy (AFM) was used to characterize the graphene nanosheets’ and the electrodes’ morphology. Charge transport characteristics of the gold-BD-graphene system were analyzed using a scanning tunneling microscope (STM), using the non-contact technique I(s). Results show that despite the asymmetric nature of the system, the I-V curve exhibits a symmetric behavior centered at 0 V. In summary, this study paves the way for the use of electrochemically exfoliated graphene nanosheets as nanoelectrodes to evaluate charge transport at the molecular level.