Assessment of the Refractive Index and Extinction Coefficient of Graphene-Poly(3-hexylthiophene) Nanocomposites

Poly(3-hexylthiophene) (P3HT) is one of the most attractive polymeric donor materials used in organic solar cells because of its high electrical conductivity and solubility in various solvents. However, its carrier mobility is low when compared to that of inorganic semiconductors; hence, the incorporation of appropriate nanomaterials to improve its electrical mobility and optical properties are pursued. In this work, a review of the changes in electrical conductivity, bandgap, hole collection properties and carrier mobility of P3HT when adding graphene (G) is presented. The main aim is to assess how the addition of different G contents influences the optical constants: refractive index (n) and extinction coefficient (k). The values of n and k as a function of the wavelength for six P3HT/G nanocomposites with G loadings in the range of 0.1-5 wt% have been fitted to two different models, Forouhi Bloomer and Cauchy, showing very good agreement between the experimental and the theoretical values. Furthermore, a rule of mixtures was successfully applied to calculate n using mass fraction instead of volume fraction, with errors lower than 6% for all the nanocomposites studied

Application of graphene-related materials in organic solar cells

Graphene-related materials (GRMs) such as graphene quantum dots (GQDs), graphene oxide (GO), reduced graphene oxide (rGO), graphene nanoribbons (GNRs), and so forth have recently emerged as photovoltaic (PV) materials due to their nanodimensional structure and outstanding properties such as high electrical and thermal conductivity, large specific surface, and unique combination of mechanical strength and flexibility. They can be a crucial part of transparent electrodes, hole/electron transport materials, and active layers in organic solar cells (OSCs). Besides their role in charge extraction and transport, GRMs act as device protectors against environmental degradation through their compact bidimensional structure and offer good durability. This review briefly presents the synthesis methods of GRMs and describes the current progress in GRM-based OSCs. PV parameters (short circuit current, open circuit voltage, power conversion efficiency, and fill factor) are summarized and comparatively discussed for the different structures. The efficiency recently surpassed 15% for an OSC incorporating polymer-modified graphene as a transparent electrode. The long-term stability of OSCs incorporating GRMs is also discussed. Finally, conclusions and the outlook for future investigation into GRM-based devices for PVs are presented

A New Method for Current-Voltage Curve Prediction in Photovoltaic Modules

In this work, a new method for obtaining the current-voltage curve for crystalline silicon and thin-film flat panels is presented. It is based on the single-diode model, with a variable shunt resistance and series resistance. New expressions for the shunt resistance and open circuit voltage as a function of the temperature and irradiance are deduced. Besides, a procedure to translate the series resistance to arbitrary conditions is proposed. The diode ideality factor and shunt resistance are obtained by optimization. The rest of the parameters that appear in the current-voltage curve are obtained from the module measurements by means of theoretical expressions. The procedure for obtaining the current-voltage curve under arbitrary operating conditions is also described. The results obtained with the developed model are compared with experimental measurements in cadmium telluride and amorphous silicon modules, and with results published in the literature for other technologies. The model faithfully reproduces the experimental values. For all the modules, the root mean square error for the maximum power is lower than 2% (below 1.5% in most cases). These errors are lower than those reported in the literature for other models. In particular, the results are significantly more exact in the case of thin-film modules

The Effect of Hexamethylene Diisocyanate-Modified Graphene Oxide as a Nanofiller Material on the Properties of Conductive Polyaniline

Conducting polymers like polyaniline (PANI) have gained a lot of interest due to their outstanding electrical and optoelectronic properties combined with their low cost and easy synthesis. To further exploit the performance of PANI, carbon-based nanomaterials like graphene, graphene oxide (GO) and their derivatives can be incorporated in a PANI matrix. In this study, hexamethylene diisocyanate-modified GO (HDI-GO) nanosheets with two di erent functionalization degrees have been used as nanofillers to develop high-performance PANI/HDI-GO nanocomposites via in situ polymerization of aniline in the presence of HDI-GO followed by ultrasonication and solution casting. The influence of the HDI-GO concentration and functionalization degree on the nanocomposite properties has been examined by scanning electron microscopy (SEM), Raman spectroscopy, X-ray di raction (XRD), thermogravimetric analysis (TGA), tensile tests, zeta potential and four-point probe measurements. SEM analysis demonstrated a homogenous dispersion of the HDI-GO nanosheets that were coated by the matrix particles during the in situ polymerization. Raman spectra revealed the existence of very strong PANI-HDI-GO interactions via - stacking, H-bonding, and hydrophobic and electrostatic charge-transfer complexes. A steady enhancement in thermal stability and electrical conductivity was found with increasing nanofiller concentration, the improvements being higher with increasing HDI-GO functionalization level. The nanocomposites showed a very good combination of rigidity, strength, ductility and toughness, and the best equilibrium of properties was attained at 5 wt % HDI-GO. The method developed herein opens up a versatile route to prepare multifunctional graphene-based nanocomposites with conductive polymers for a broad range of applications including flexible electronics and organic solar cells

Pvlearning: herramienta web para la enseñanza de la energía solar fotovoltaica

En este trabajo, se describe la web www.pvlearning.com, desarrollada en la Universidad de Alcalá para la enseñanza de la energía solar fotovoltaica. PVLEARNING asiste al alumno en la realización de tareas como la evaluación de la radiación solar disponible, la selección de los componentes del sistema, la configuración de éstos y la estimación del rendimiento global y la energía total producida. Frente a otros programas de simulación, la plataforma presenta la novedad de estar enfocada al aprendizaje de la ingeniería de proyectos, sin por ello perder todo el rigor y la funcionalidad necesarios en este tipo de simuladores.This work describes the web www.pvlearning.com, which has been developed at the Universidad de Alcalá for photovoltaic solar energy teaching. PVLEARNING assists the student in tasks such as the evaluation of the solar radiation, the selection of the system components, the configuration of the solar generator and the estimation of the performance ratio, the final yield and the total energy production. In contrast to other simulation programs, the platform has the novelty of being focused on the learning of project engineering, without losing the accuracy and functionality which is required in this kind of simulator

Utilización de wikis como recurso docente en estudios universitarios de Ingeniería en Telecomunicación

[EN] A wiki is an easy-to-use on-line tool for teachers and students. This free software allows users to edit its pages in asynchronous way, with no need for users to work as the same place nor time. The main goal of using wikis at the University is to achieve collaboration among students for generating material of a subject. This methodology turns the students into exclusive publishers and takes them responsibility for the end product, which encourages the self-control and the self-management of the learning process. The contents in a wiki cover a wide spectrum: notes of the subject, tests, audio-visual material or exercises proposed to solve in a collaborative way. The teacher has to provide feedback to the students in order to guide them and make sure the knowledge in the wiki is not mistaken.[ES] Una wiki es una herramienta on-line de uso sencillo para profesores y alumnos. Este software gratuito permite la edición de páginas web a todos los usuarios, no requiriendo coincidencia ni espacial ni temporal. El objetivo principal para su empleo en docencia universitaria es lograr la colaboración entre estudiantes en la generación de contenidos. Con esta metodología los estudiantes se convierten en los editores exclusivos y responsables directos del producto final, fomentando así el autocontrol y la autogestión sobre su propio aprendizaje. Los contenidos a desarrollar en una wiki cubren un amplio espectro: apuntes de la asignatura, ensayos, material audiovisual o ejercicios propuestos para resolver de forma colaborativa. El profesorado que asiste la wiki proporciona feedback a sus alumnos, los tutoriza y guía velando por la veracidad del material.García Díaz, M.; Díez Pascual, A.; Ortega Núñez, M.; Cambralla Diana, R.; Peña Capilla, R. (2017). Utilización de wikis como recurso docente en estudios universitarios de Ingeniería en Telecomunicación. En In-Red 2017. III Congreso Nacional de innovación educativa y de docencia en red. Editorial Universitat Politècnica de València. 219-230. https://doi.org/10.4995/INRED2017.2017.6853OCS21923

Convergence of guided learning and autonomous learning in the final evaluation

[EN] A learning experience carried out in the first course of Engineering Degrees at the University of Alcalá is presented. The objective is to mentor, reinforce and assist in the learning process of a subject that the student should study for an extraordinary call exam when the teaching of that subject has already finished. Students usually work alone in the preparation of this evaluation and it has been demonstrated that the academic scores are on average are worse than in the ordinary call, the latter one being closer to the teaching received. A working plan has been established with pseudo-weekly supervision of a group of 70 students. All of them were volunteers. The results show a correlation between participation in the supervised group and the highest grades achieved in the evaluation, grades of "B" and "A". The coexistence of two tendencies is suggested: on the one hand, the student more committed to the subject is more likely to enroll in the mentoring group, and on the other hand, the teacher's support contributes to improve the academic achivements.[ES] Se presenta una experiencia de aprendizaje realizada en el primer curso de Grados en Ingeniería en la Universidad de Alcalá. El objetivo es guiar, reforzar y acompañar en el proceso de aprendizaje de una asignatura que el estudiante debiera prepararse para un examen de convocatoria extraordinaria cuando la docencia de dicha asignatura haya finalizado. Habitualmente los estudiantes caminan solos hacia la evaluación y los resultados académicos son peores que en la convocatoria ordinaria, próxima en el tiempo a la docencia recibida. Se ha establecido un plan de trabajo con seguimiento cuasi-semanal sobre un grupo de 70 estudiantes que participaron voluntariamente. Los resultados muestran correlación entre la participación en el grupo de seguimiento y las calificaciones más altas obtenidas en la evaluación: notable y sobresaliente. Se sugiere la coexistencia de dos tendencias: por un lado, el estudiante con mayor motivación hacia la asignatura es más proclive a incorporarse al grupo tutelado; por otro, el apoyo del docente contribuye a mejorar los logros académicos.Los autores expresan su agradecimiento al proyecto de innovación docente UAH/EV1248 de la Universidad de Alcalá, implementado por el grupo de innovación docente ABRECI (Aprendizaje Basado en Retos en Ciencias e Ingeniería, UAH-GI21-168).García-Díaz, P.; Díez-Pascual, A.; Jurado-Sánchez, B.; Peña-Capilla, R. (2022). Convergencia del aprendizaje dirigido y del aprendizaje autónomo en la evaluación final. Editorial Universitat Politècnica de València. 173-183. https://doi.org/10.4995/INRED2022.2022.1583817318

Herramientas Software para Enseñanzas Relacionadas con la Energía Solar Fotovoltaica

[EN] This paper describes different simulation tools developed in the Universidad de Alcalá in order to teach photovoltaic energy engineering. A web application is compared to other tools, such as spreadsheets and applications in Matlab environment, developed by the authors. In all the cases, the tools are focused on learning project engineering.[ES] En este trabajo, se describen diferentes herramientas de simulación empleadas en asignaturas de la Universidad de Alcalá para la enseñanza de la energía solar fotovoltaica. Se compara el uso de una aplicación web con otras herramientas como hojas de cálculo y aplicaciones en entorno Matlab. Todas las herramientas descritas han sido desarrolladas por los autores, haciendo especial énfasis en su enfoque didáctico, sin por ello perder todo el rigor y la funcionalidad necesarios en este tipo de simuladores.Peña Capilla, R.; García Díaz, M.; Alén Cordero, C.; Díaz Villar, P.; Mallol Poyato, R.; Díez-Pascual, A. (2017). Herramientas Software para Enseñanzas Relacionadas con la Energía Solar Fotovoltaica. En In-Red 2017. III Congreso Nacional de innovación educativa y de docencia en red. Editorial Universitat Politècnica de València. 1311-1321. https://doi.org/10.4995/INRED2017.2017.6862OCS1311132

Empoderamiento del alumnado adulto y de las personas mayores para una ciudadanía activa

Esta obra reúne iniciativas y experiencias de sensibilización y formación del profesorado y del alumnado adulto y mayor hacia una educación en competencias que contribuya a desarrollar la práctica de una ciudadanía activa compartiendo el tiempo libre, los conocimientos y las experiencias en proyectos sociales que consoliden y mejoren el entramado social de la ciudad, de las personas que la habitan y de la atención a sus necesidades. Su origen fue el proyecto CiudAct cofinanciado por el Programa Erasmus+ de la Unión Europea y en su desarrollo ha intervenido un equipo interinstitucional liderado por el Aula de Mayores+55 de la Universidad de Málaga y participado por el Centro de Profesorado «José Rodríguez Galán» de Antequera, la Asociación Cívica para la Prevención (ACP), la Asociación de Igualdad de Género Universitario (AIGU), y el Ayuntamiento de Faraján (Málaga). Con ellos, y con otras tantas instituciones y sus respectivos consorcios locales en toda Europa, se participa en la red supranacional Ciudades en Crecimiento.Programa Erasmus+ de la Unión Europea (referencia de proyecto 2015-1-ES01-KA104-014944

Semiconductor materials for photovoltaic converters applied to power-by-light systems

The purpose of this work is to asses the commonly used semiconductor materials in order to manufacture photovoltaic converters for optical powering links. Aspects such as the output voltage, conversion efficiency, device size, etc, will be reviewed, comparing the suitability of the different materials for these power receivers.Sin financiaciónNo data (2005)UE