Effect of impurities on pentacene island nucleation

Pentacenequinone (PnQ) impurities have been introduced into a pentacene source material in a controlled manner to quantify the relative effects of the impurity content on grain boundary structure and thin film nucleation. Atomic force microscopy (AFM) has been employed to directly characterize films grown using 0.0-7.5% PnQ by weight in the source material. Analysis of the distribution of capture zones areas of submonolayer islands as a function of impurity content shows that for large PnQ content the critical nucleus size for forming a Pn island is smaller than for low PnQ content. This result indicates a favorable energy for formation of Pn-PnQ complexes, which in turn suggests that the primary effect of PnQ on Pn mobility may arise from homogeneous distribution of PnQ defects.Comment: 16 Pages, 5 figures, 1 Tabl

Effect of Impurities on Pentacene Thin Film Growth for Field-Effect Transistors

Pentacenequinone (PnQ) impurities have been introduced into a pentacene source material at number densities from 0.001 to 0.474 to quantify the relative effects of impurity content and grain boundary structure on transport in pentacene thin-film transistors. Atomic force microscopy (AFM) and electrical measurements of top-contact pentacene thin-film transistors have been employed to directly correlate initial structure and final film structures, with the device mobility as a function of added impurity content. The results reveal a factor four decrease in mobility without significant changes in film morphology for source PnQ number fractions below ~0.008. For these low concentrations, the impurity thus directly influences transport, either as homogeneously distributed defects or by concentration at the otherwise-unchanged grain boundaries. For larger impurity concentrations, the continuing strong decrease in mobility is correlated with decreasing grain size, indicating an impurity-induced increase in the nucleation of grains during early stages of film growth.Comment: 18 pages, 4 Figures, 1 Tabl

Organitzacions de tetratiafulvalens a escala nanomètrica

El projecte de tesis se centra en la síntesi, caracterització i estudi de les propietats estructurals, elèctriques, magnètiques i òptiques de noves organitzacions moleculars en dos i tres dimensions basades en compostos derivats del tetratiafulvalè (TTF). El treball es divideix en dues estratègies:- Per una part, en la sínetsi d'isocianurs quirals que incorporen unitats de tetratiafulvalè per la síntesis de poli(isocianur)s helicoïdals quirals conductors.- I per l'altra, en la preparació de nous TTFs que poden formar agregats supramoleculars per auto-ensamblatge sobre grafit i altres superficies, i el seu estudi estructural mitjançant les técniques de microscopia d'escombrat per efecte túnel (STM, scanning tunneling microscopy) i microscopia de força atómica (AFM, atomic force microscopy). Així com l'estudi de les propietats elèctriques d'aquets agregats mitjançant les tècniques d'espectroscopia d'efecte túnel (STS, scanning tunneling spectroscopy) i cs-AFM (current sensing atomic force microscopy).Design, chemical synthesis, structural and electronic characterization, materials preparation, study of new organic molecular and supramolecular materials based on tetrathiafulvalene derivatives showing novel electrical, magnetic and optical properties. Two strategies were followed:- Synthesis of chiral tetrathiafulvalens derivatives funcionalized with an isocyanide group to prepare conducting enanthiomeric helical poly(isocyanides).- Preparation and electrical-structural characterization of TTF self-assembled monolayers on surfaces - graphite and gold - using ellipsometry, single reflection ATR infrared spectrocopy, contact angle, scanning tunneling microscopy (STM) and atomic force microscopy (AFM)

Organitzacions de tetratiafulvalens a escala nanomètrica

Consultable des del TDXTítol obtingut de la portada digitalitzadaEl projecte de tesis se centra en la síntesi, caracterització i estudi de les propietats estructurals, elèctriques, magnètiques i òptiques de noves organitzacions moleculars en dos i tres dimensions basades en compostos derivats del tetratiafulvalè (TTF). El treball es divideix en dues estratègies: - Per una part, en la sínetsi d'isocianurs quirals que incorporen unitats de tetratiafulvalè per la síntesis de poli(isocianur)s helicoïdals quirals conductors. - I per l'altra, en la preparació de nous TTFs que poden formar agregats supramoleculars per auto-ensamblatge sobre grafit i altres superficies, i el seu estudi estructural mitjançant les técniques de microscopia d'escombrat per efecte túnel (STM, scanning tunneling microscopy) i microscopia de força atómica (AFM, atomic force microscopy). Així com l'estudi de les propietats elèctriques d'aquets agregats mitjançant les tècniques d'espectroscopia d'efecte túnel (STS, scanning tunneling spectroscopy) i cs-AFM (current sensing atomic force microscopy).Design, chemical synthesis, structural and electronic characterization, materials preparation, study of new organic molecular and supramolecular materials based on tetrathiafulvalene derivatives showing novel electrical, magnetic and optical properties. Two strategies were followed: - Synthesis of chiral tetrathiafulvalens derivatives funcionalized with an isocyanide group to prepare conducting enanthiomeric helical poly(isocyanides). - Preparation and electrical-structural characterization of TTF self-assembled monolayers on surfaces - graphite and gold - using ellipsometry, single reflection ATR infrared spectrocopy, contact angle, scanning tunneling microscopy (STM) and atomic force microscopy (AFM)