Study of the Geometry and Electronic Structure of Self-Assembled Monolayers on the Au(111) Surface

Abstract

[EN]A study of the geometries and electronic properties of organic molecular thin films adsorbed on Au(111) has been presented in this thesis. It contains DFT-based first principles calculations, that have been compared to experimental results, mainly STM/STS measurements. Three different systems have been analysed in detail: chemisorption of small thiolates, donor–acceptor charge-transfer complex adsorption, and co-adsorption of complementary polyarenes. These systems cover a wide range of the different strategies used to grow SAMs. Indeed, the relative strength of the interactions that steer the selfassembly of such films, ranging from strong to weak adsorbate–substrate interactions with distinct adsorbate–adsorbate interactions, results in a perfect playground to understand the underlaying physics in the formation of SAMs. With that aim we have used different theoretical tools throughout this work, that include, besides relaxed geometries and energetic analysis, induced electron densities, PDOS on atomic sites and molecular orbitals, band structure calculations, charge transfer analysis, etc.

[ES]Esta tesis presenta un estudio teórico, mediante el formalismo de teoría funcional de densidad (dft), de las geometrías y propiedades electrónicas de films delgados de moléculas orgánicas adsorbidad en Au(111). En función de la intensidad relativa de las interacciones adsorvato-adsorbato y adsorbato-substrato, que gobiernan el autoensamblado de dichos films, tres sistemas diferentes son analizados en detalle: quimisorcion de pequeños thiolatos, adsorción de complejos donor-acceptor, y co-adsorción de poliarenos complemetarios. Con el objetivo de entender la física subyacente en la formacion de monocapas autoensambladas, resultados experimentales disponibles (principalmente medidas STM y STS) son contrastados gracias al uso de distintas herramientas teóricas, que incluyen, proyección de densidad de estados en orbitales atómicos y moleculares, cálculo de la estructura de bandas, transferencia de carga, etc.