Organic ambipolar semiconductors for TFT applications

In the last years we have devoted some effort to the search of new high-mobility semiconductors with ambipolar performances, good processability and environmental stability. Our approach, which is one of the most widely used, consists in the combination of donor and acceptor moieties in the conjugated skeleton, which allows fine tuning of the frontier molecular orbitals. For OTFT applications, low-lying HOMOs are essential to resist air oxidation and thus increase device stability. However, if the HOMO energy is too low, the resulting barrier to hole injection may compromise the transistor performance. Thus, a delicate balance between these two effects is needed. In particular, we have combined naphthaleneimide-derived moieties as electron accepting groups with electron-rich oligothiophene fragments. In these materials, we have found that the presence of ambipolar transport in these planar molecules can be understood on the basis of three interrelated properties: (i) the absence of skeletal distortions allows closer intermolecular pi-pi stacking and enhanced intramolecular pi-conjugation, (ii) increased pi-conjugation raises the HOMO energy, which approaches the Fermi level of common used electrodes; and (iii) more planar structures translate into lower Marcus reorganization energies. However, one of the limitations of these types of semiconductors is the presence of a molecular dipole moment, which forces the molecules to pack with pairwise intermolecular interactions orienting the naphthaleneimide cores in opposite directions, decreasing in some cases molecular orbitals overlapping. In recent contributions, we have devoted our efforts to analyze the effect of molecular interactions, through chemical modifications in order to induce parallel and antiparallel molecular packing, on the electronic properties of ambipolar semiconductors.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Understanding organic materials performance in field-effect transistors

Comunicación oralIn the last years, much of our effort has been devoted to the search and study of new high-mobility semiconductors for organic thin film transistors. The approach used for the materials design has been two-fold: (i) the combination of donor and acceptor moieties in the pi-conjugated skeleton, which allows fine tuning of the frontier molecular orbitals, being this necessary for achieving electron/hole or ambipolar transport and ambient stability; and (ii) rational selection of the type and positioning of specific solubilizing substituents ensuring processability, which is essential to make these materials scalable to industry. However, material processability should be attained minimizing a negative effect on charge transport. Therefore, proper energy levels, planar molecular conformations, close intermolecular pi-pi stacking and adequate thin film crystallinity need to be maintained upon alkyl substitution. In this communication, several examples of molecular and polymeric materials are shown. A rational design, guided by experimental and theoretical evidences, has prompted modifications on their conjugated skeletons, donor/acceptor subunits ratio and/or selection of proper alkyl solubilizing chains, which induce noticeable changes in their electronic performances. The main aim of these studies is the basic understanding of charge transport in organic materials. For this end, we will use Raman spectroscopy and DFT quantum-chemical calculations as important tools for materials characterization.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Uniform relations between the Gauss-Legendre nodes and weights

Three different relations between the Legendre nodes and weights are presented which, unlike the circle and trapezoid theorems for Gauss-Legendre quadrature, hold uniformly in the whole interval of orthogonality $(-1,1)$. These properties are supported by strong asymptotic evidence.The study of these results is motivated by the role they play in certain finite difference schemes used in the discretization of the angular Fokker-Planck diffusion operator

Analysis of difference schemes for the Fokker-Planck angular diffusion operator

This paper is dedicated to the mathematical analysis of finite difference schemes for the angular diffusion operator present in the azimuth-independent Fokker-Planck equation. The study elucidates the reasons behind the lack of convergence in half range mode for certain widely recognized discrete ordinates methods, and establishes sets of sufficient conditions to ensure that the schemes achieve convergence of order $2$. In the process, interesting properties regarding Gaussian nodes and weights, which until now have remained unnoticed by mathematicians, naturally emerge.Comment: 35 pages, 1 figure, 2 subfigure

Governing Juana: Madness and Manipulation of Power in Three Spanish American Plays on Juana la Loca

This article examines the representation of Juana of Castile in three twentieth-century Spanish American plays — Zavalía’s El corazón extraviado — (Argentina, 1957), Sabido’s Falsa crónica de Juana la Loca (Mexico, 1985), and Rueda’s Retablo de la pasión y muerte de Juana la Loca (Dominican Republic, 1996) — that portray the queen sympathetically as the victim of elaborate plots to usurp her authority. While the plays expose her madness as a pretext used by her father King Fernando and her son Emperor Carlos V to confine her for nearly half a century in the palace of Tordesillas, they do not deny the basic premises of the official history of “Juana la loca.” Thus, the captive queen is represented on stage as not only unable to govern Spain, but also as unable to control herself, leading others to “govern Juana.” (KL and AMS, Article in English

Comparación de dos métodos de evaluación simplificada del riesgo químico por inhalación en un laboratorio universitario (COSHH Essentials y método basado en el INRS)

En conclusión, hemos comprobado que ambos métodos pueden ser un recurso sencillo para planificar la prevención en entornos laborales con riesgo químico. El método basado en el INRS contempla más determinantes del riesgo que el COSHH Essentials, pero las características dispares de ambos métodos deben determinar la mejor elección para cada situación; o incluso, como sugieren nuestros resultados, su utilización complementaria. Se debe añadir que, "es razonable iniciar el proceso de evaluación con un análisis cualitativo, a pesar de que, en muchas ocasiones no es posible alcanzar conclusiones sobre el riesgo y es necesario realizar una evaluación cuantitativa"; también sería recomendable, ante situaciones que se conoce que presentan riesgo, y los resultados de las mediciones se van a demorar para establecer las medidas preventivas necesarias con antelación

Notas sobre la revuelta mudéjar de 1490. El caso de Fiñana.

Sin resume

Prototipo de aplicativo para especificar requerimientos de software

Trabajo de InvestigaciónLa especificación de requerimientos para un desarrollo eficaz del producto necesario en una empresa o entidad es de gran importancia, tanto para los intereses económicos como para resolver los problemas que el proyecto plantea. Este trabajo de grado está pensado y desarrollado para minimizar los errores en la especificación de requerimientos de negocio a través de un aplicativo, diseñado para que el Core del negocio es decir, la parte donde el cliente recita las expectativas del proyecto, sea lo más objetiva posible, concediendo al grupo de analistas una mejor idea del producto final que se quiere implementar.INTRODUCCIÓN 1. PLANTEAMIENTO DEL PROBLEMA 2. OBJETIVOS DEL PROYECTO 3. MARCO REFERENCIAL 4. METODOLOGÍA PROPUESTA 5. LECTURA DE PAPERS 6. DESARROLLO DEL PROYECTO 7. CONCLUSIONES BIBLIOGRAFÍA ANEXOSPregradoIngeniero de Sistema