Direct observation of gradual molecular level alignment of Fe Pcs on a gold electrode

Resumen del póster presentado a la Conferencia bienal Fuerzas y Túnel, celebrada en Jaca (España) del 27 al 29 de junio de 2018.
One of the key prerequisite for the optimal performance of organic opto-electronic devices is an efficient charge-carrier transport into and out of the organic semiconductor material. Carrier injection in turn strongly depends on the molecular level alignment of the organic semiconductor material against the fermi level of the conducting electrodes. In a recent work we studied the evolution of molecular levels of Fe-phthalocyanine with increasing layer thickness on a gold (111) surface. By means of STM and STS we found that beyond the strong hybridization of the electronic states of the 1st molecular monolayer with the metallic substrate, the gap between the frontier orbitals is still strongly influenced at the 5th mono layer away from the surface. This sequential decrease of the HOMO-LUMO gap towards the metallic electrode should strongly support the charge-carrier injection for this kind of materials. Accordingly, such a layer- wise STM/STS investigation can give a detailed atomistic insight into electronic processes at metal/organic interfaces towards the bulk material and might help to improve the design of organic opto-electronic devices.