Study of the geometry and electronic structure of self-assembled monolayers on the Au(111) surface

Doctoral Thesis submitted to the University of the Basque Country for the Degree of Doctor in Physics by Nora Gonzalez Lakunza.[ES]: Esta tesis presenta un estudio teórico, mediante el formalismo de teoría del funcional de densidad (DFT), de las geometrías y propiedades electrónicas de films delgados de moléculas orgánicas adsorbidas en Au(111). En función de la intensidad relativa de las interacciones adsorbato-adsorbato y adsorbato-substrato, que son las interacciones que gobiernan el autoensamblado de dichos films, han sido analizados en detalle tres sistemas distintos: quimisorción de pequeños thiolatos (azufre, y móleculas simples con azufre), adsorción de complejos de trasferencia de carga donor-acceptor (tetrathiafulvalene, TTF y 7,7,88-tetracyanoquinodimethane, TCNQ), y coadsorción de poliarenos con grupos funcionales complementarios amina y imida (1,4-bis(4,6-diamino-1,2,5-triazin-2-yl)benzene, BDG y naphtalene tetracarboxylic diimide, NTCDI). Con el objetivo de entender la física subyacente en la formación de dichas monocapas autoensambladas, resultados experimentales disponibles (principalmente medidas de STM y STS) son contrastados gracias al uso de distintas herramientas teóricas, que incluyen, aparte de geometrías relajadas y análisis energético, densidades electrónicas inducidas, proyección de densidad de estados en orbitales atómicos y moleculares, cálculo de la estructura de bandas, transferencia de carga, etc.[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.Peer reviewe