Development of RTP processing for kesterite solar cells

[eng] This thesis is devoted to the development of new annealing strategies via Rapid Thermal Processing (RTP) for Earth-abundant Cu2ZnSn(Sx,Se1-x) (CZTSSe) kesterite solar cells, which show a clear consensus amongst the scientific community as one of the most suitable production techniques for a posterior industrial implementation. RTP contains several advantages, mostly summarized in: the employment of fast heating halogen lamps in common with the industry, better suited for obtaining an accurate control of the process and the obtainment of high Se vapour pressures since the very beginning of the annealing, which in this thesis have been proven to have strong impacts on the final device characteristics. This thesis is englobed into the so-called sequential processes where the precursor and the absorber are obtained in different steps. It has been developed and optimized an annealing process for the baseline established at IREC, where the precursor is synthesized via sputtering and later annealed in a furnace. The aim of the developed annealing strategy has consisted on obtaining the fastest annealing possible without compromising the final efficiency and properties of the solar cell. Thanks to the annealing procedure stablished in this thesis, it could be reached up to 8.3% efficiency in an only 12 minutes annealing process. Once an RTP annealing procedure was developed and optimized, it was of key importance to deeply understand and comprehend the insights into the process and the formation pathways to synthesize the kesterite on it. In order to do so, the process was stopped at several intermediate key steps and strongly characterized, depicting the very early formation of the kesterite and that the kesterite synthesis process, for the RTP annealing procedure at IREC, it is driven by a competition between two formation mechanisms (ruled either via ternary or binary compounds). In this thesis is stated and commented why the formation mechanism driven by the ternary compound is preferred over the one ruled via binaries. In this thesis it is also provided a study about the kinetics present on the RTP process, where the kinetic orders for the different formation mechanisms to synthesize the kesterite are analysed, complemented by a deep and extensive analyse of the phases present through the process. By the combination of the kinetic and phase analysis, it is concluded that even the less favourable formation mechanism driven by binaries compounds can be reduced to a marginal extent yet it can never be completely overcome as it is always present. This process might end into detrimental secondary phases for the devices final performing, endorsing the necessity of extra processing steps such as chemical etchings to counteract their effects. Finally, in order to study the robustness of the annealing process stablished through this thesis, the RTP annealing process has been tested onto precursors synthesized by electrodeposition, instead of sputtering as usual in IREC’s standard baseline. Electrodeposited precursors have been obtained by the co-electrodeposition approach and later submitted to the RTP annealing. Efficiencies up to 5.2% have been achieved by this combination, which are the highest reported by this sequence so far, proving the robustness of the RTP annealing procedure developed and optimized in this thesis.[spa] Esta tesis estudia el desarrollo de nuevas estrategias de recocido por Rapid Thermal Procesing (Procesos de Recocido Rápidos) para celdas solares de kesterita, Cu2ZnSn(Sx,Se1-x) (CZTSSe), gracias a que las celdas de kesterita únicamente poseen en su estructura materiales abundantes en la corteza terrestre y además, la producción por RTP es una de las técnicas que posee mayor consenso entre la comunidad científica para una plausible aplicación industrial posterior. Para la síntesis de la kesterita, la línea desarrollada en IREC se basa en los procesos secuenciales. En ellos se obtiene el precursor por sputtering y el absorbedor mediante hornos en etapas claramente diferenciadas. En esta tesis se presenta el estudio del desarrollo y optimización de un proceso de recocido basado en dos etapas por RTP, donde se busca minimizar el tiempo de recocido, sin comprometer las propiedades de la celda solar. Con susodicho proceso, se han llegado a obtener celdas con eficiencias de hasta 8.3% con un tiempo de recocido de solamente 12 minutos. A continuación, se presenta un estudio en profundidad sobre los entresijos del proceso de recocido, ayudando a esclarecer las partes intermedias del proceso, concluyendo que el proceso de síntesis de la kesterita procede por una competición entre mecanismos: el mecanismo dirigido por compuestos ternarios y el segundo por compuestos binarios. En la presente tesis se provee además con un estudio sobre la cinética de reacción para la síntesis de la kesterita por RTP, presentando los órdenes de reacción y concluyendo mediante un exhaustivo análisis de fases que no es posible la completa erradicación de los compuestos binarios para la síntesis de la kesterita. Finalmente, para estudiar la robustez del proceso de recocido desarrollado por RTP, ha sido extendido a precursores obtenidos por otra técnica de síntesis, en este caso la técnica escogida ha sido la del electrodepósito. Mediante el uso de precursores obtenidos por co-electrodepósito y su posterior recocido por RTP, se ha demostrado la robustez del proceso desarrollado en esta tesis al obtener eficiencias de hasta el 5.2%, la más alta reportada con esta secuencia

Coagulación intravascular diseminada: Una revisión de tema

Introduction: Disseminated intravascular coagulation is a secondary syndrome to underlying pathologies, where localized coagulation activation and generalized inflammatory response can lead to tissue and microvascular damage. A prevalence of 10.8% has been reported in several intensive care units in Colombia. Its presentation in the context of sepsis is different depending on the type of infection. Objective: To conduct a review of literature of the most outstanding concepts of disseminated intravascular coagulation. Materials and methods: A review was made by means of the search of original articles, systematic and narrative reviews, in the PubMed and ScienceDirect databases and in the Google Scholar search engine; 80 articles were selected, of which 51 were included. Publications were taken into account in Spanish, English and French, with a publication date of less than or equal to 5 years. Results: The description of treatment, etiology, clinical presentation and diagnosis of Disseminated Intravascular Coagulation was made, with special emphasis on the studies on molecular markers and new therapeutic alternatives. Conclusion: Disseminated intravascular coagulation is a complication which contributes to increase morbidity and mortality, whose early diagnosis and treatment contribute significantly to better clinical evolution

Una propuesta curricular para la implementación de un taller de aplicaciones matemáticas en ingeniería

Dentro del marco teórico de la enseñanza por proyectos (La Cueva, 2001; Malaspina, 2007), se presenta una asignatura curricular llamada taller de aplicaciones matemáticas en la cual se realizan aplicaciones generales de tipo básico, aplicaciones relacionadas con la ingeniería en general y aplicaciones específicas a cada tipo de ingeniería de las impartidas en la Unidad Profesional Interdisciplinaria de Biotecnología (UPIBI). Los alumnos hacen uso de sus antecedentes matemáticos y resuelven problemas de aplicación en un ambiente cooperativo, construyen por si mismos los modelos de los problemas a resolver. Se trabaja y evalúa por medio de proyectos en los cuales se fomenta el aprendizaje cooperativo, el compromiso de los estudiantes y la creatividad. La evaluación es continua, las tareas son proyectos cortos y no hay exámenes. Los alumnos preparan por equipo un proyecto más extenso que prepara en una o dos semanas y cuyos resultados presentan en una sesión pública donde son evaluados a partir de la presentación, de la entrega detallada de un reporte escrito con sus resultados y de su desempeño en la sesión de preguntas. Además de la propuesta se presentan resultados preliminares porque ya se implementado la asignatura

The communication of a football club: The case of Hércules de Alicante C.F.

Este trabajo analiza la comunicación de un club de fútbol, en este caso el Hércules de Alicante Club de Fútbol, que actualmente milita en una categoría semiprofesional como es la Segunda División B. Desde la llegada de Tomás Moya como director de comunicación el club ha realizado numerosos avances a nivel comunicativo necesarios para su profesionalización, aunque, si el club compitiese en una liga profesional, podría disponer de un equipo que mejorase la comunicación. La metodología de trabajo ha consistido en una investigación exhaustiva a través de redes sociales, su canal de YouTube y su página web. También se realizaron dos entrevistas, al director de comunicación del club, y al jefe de deportes de la Cadena Cope Alicante. La prueba del crecimiento del club a nivel comunicativo se ve reflejado en el aumento de seguidores en todas sus plataformas.This work analyzes the communication of a club, in this case the Hércules de Alicante Club de Fútbol, that currently plays in a semi-professional category like is the Segunda División B. From the arrivals of Tomás Moya like a communications manager the club has made many advances that were unthinkable with the previous director of communication, although, if the club competed in a professional league, it could have a team that improved communication. The methodology of work was to carry out a thorough investigation social networks, the YouTube channel and the website. There were also two interviews, the communication manager, and the head of the section of sports of the Cadena Cope Alicante. The proof of the club's growth at the communicative level has been reflected in the increase of followers in all its platforms

Cladobotryum mycophilum as Potential Biocontrol Agent

A study was conducted to explore the efficacy of potential biocontrol agent Cladobotryum mycophilum against different phytopathogenic fungi. The growth rates of 24 isolates of C. mycophilum were determined, and their antagonistic activity was analysed in vitro and in vivo against Botrytis cinerea, Fusarium oxysporum f. sp. radicis-lycopersici, Fusarium oxysporum f.sp. cucumerinum, Fusarium solani, Phytophthora parasitica, Phytophthora capsici, Pythium aphanidermatum and Mycosphaerella melonis. Most isolates grow rapidly, reaching the opposite end of the Petri dish within 72–96 h. Under dual-culture assays, C. mycophilum showed antagonistic activity in vitro against all phytopathogenic fungi tested, with mycelial growth inhibition ranging from 30 to 90% against all the different phytopathogens tested. Similarly, of all the selected isolates, CL60A, CL17A and CL18A significantly (p < 0.05) reduced the disease incidence and severity in the plant assays compared to the controls for the different pathosystems studied. Based on these results, we conclude that C. mycophilum can be considered as a potential biological control agent in agriculture. This is the first study of Cladobotryum mycophilum as a biological control agent for different diseases caused by highly relevant phytopathogens in horticultur

Plant Growth Promotion and Biocontrol of Pythium ultimum by Saline Tolerant Trichoderma Isolates under Salinity Stress

This present study evaluates three isolates of Trichoderma as plant growth promoting or biological control agents: Trichoderma aggressivum f. sp. europaeum, Trichoderma saturnisporum, and the marine isolate obtained from Posidonia oceanica, Trichoderma longibrachiatum. The purpose is to contribute to an overall reduction in pesticide residues in the fruit and the environment and to a decrease in chemical fertilizers, the excess of which aggravates one of the most serious abiotic stresses, salinity. The tolerance of the different isolates to increasing concentrations of sodium chloride was evaluated in vitro, as well as their antagonistic capacity against Pythium ultimum. The plant growth promoting capacity and effects of Trichoderma strains on the severity of P. ultimum on melon seedlings under saline conditions were also analysed. The results reveal that the three isolates of Trichoderma, regardless of their origin, alleviate the stress produced by salinity, resulting in larger plants with an air-dry weight percentage above 80% in saline stress conditions for T. longibrachiatum, or an increase in root-dry weight close to 50% when T. aggressivum f. sp. europaeum was applied. Likewise, the three isolates showed antagonistic activity against P. ultimum, reducing the incidence of the disease, with the highest response found for T. longibrachiatum. Biological control of P. ultimum by T. aggressivum f. sp. europaeum and T. saturnisporum is reported for the first time, reducing disease severity by 62.96% and 51.85%, respectively. This is the first description of T. aggressivum f. sp. europaeum as a biological control agent and growth promoter. The application of these isolates can be of enormous benefit to horticultural crops, in both seedbeds and greenhouses

Yield and Selectivity Improvement in the Synthesis of Carbonated Linseed Oil by Catalytic Conversion of Carbon Dioxide

Artículo derivado de trabajo de tesis de doctoradoCarbonation of epoxidized linseed oil (CELO) containing five‐membered cyclic carbonate (CC5) groups has been optimized to 95% by reacting epoxidized linseed oil (ELO) with carbon dioxide (CO2) and tetrabutylammonium bromide (TBAB) as catalysts. The effect of reaction variables (temperature, CO2 pressure, and catalyst concentration) on the reaction parameters (conversion, carbonation and selectivity) in an autoclave system was investigated. The reactions were monitored, and the products were characterized by Fourier Transform Infrared Spectroscopy (FT‐IR), carbon‐13 nuclear magnetic resonance (13C‐NMR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopies. The results showed that when carrying out the reaction at high temperature (from 90 °C to 120 °C) and CO2 pressure (60–120 psi), the reaction’s conversion improves; however, the selectivity of the reaction decreases due to the promotion of side reactions. Regarding the catalyst, increasing the TBAB concentration from 2.0 to 5.0 w/w% favors selectivity. The presence of a secondary mechanism is based on the formation of a carboxylate ion, which was formed due to the interaction of CO2 with the catalyst and was demonstrated through 13C‐NMR and FT‐IR. The combination of these factors makes it possible to obtain the largest conversion (96%), carbonation (95%), and selectivity (99%) values reported until now, which are obtained at low temperature (90 °C), low pressure (60 psi) and high catalyst concentration (5.0% TBAB).Secretaría de Investigación y Estudios Avanzados 4965/2020CI

Primeras acciones para el uso de energías limpias en Tlaxcala, México. Ventajas y desventajas

Energy is fundamental to the system of nature, where the subsystem of the economy converges in its processes through inputs and outputs of matter. Maintaining an energy balance is the current approach to ecological economics, where the transition to clean energy is proposed to achieve a balance between economic activity and the environment. The governments have set investment in renewable energy as a global objective, in Tlaxcala through private investment this process has begun through the installation of photovoltaic plants with the “Macroparque la Magdalena II”.La energía es fundamental para el sistema de la naturaleza, donde el subsistema de la economía converge en sus procesos por medio de entradas y salidas de materia. Mantener un balance energético es el actual enfoque de la economía ecológica, donde se plantea la transición a energías limpias para lograr el equilibrio entre la actividad económica y el medio ambiente. Los gobiernos han puesto como objetivo global la inversión en energías renovables, en Tlaxcala por medio de inversión privada se ha iniciado con tal proceso con la instalación de plantas fotovoltaicas, el proyecto “Macroparque la Magdalena II”

Dynamic Analysis of Hypar Membrane Structures Subjected to Seismic Excitations

The seismic response of tensile membrane structures (TMS) is investigated. To the authors knowledge, this is the first study on TMSs subjected to a seismic record reported in the literature. A type of membrane structures usually considered as a reference in other works are employed in the present study. The selected hyperbolic-paraboloid fabric structures, also referred as hypar TMSs, are subjected to an earthquake accelerogram from a relatively large earthquake recorded at Norcia, Italy. To obtain the TMSs seismic response, a finite element formulation reported in a previous study, and which accounts for wrinkling phenomena, orthotropic material modeling, and geometrical nonlinearity, is employed. The analyses are performed in two stages; first for the prestressed case and then the seismic loading is added. It is found that the seismic response of TMSs should not be disregarded by designers beforehand, since important increments in the dynamic response of the displacements produce an incremet of around 9% for stresses. However, a very important increment of around 80% for support reaction forces is computed, when compared with the static case. It is also found that the orientation of the frame-supporting structure has a significant impact on the computed seismic reactions.Peer Reviewe

Diagnosis of audiovisual information processing in local television archives. Case study in Cuba

Los archivos audiovisuales en televisoras locales favorecen el procesamiento y conservación de la información audiovisual para su posterior recuperación. El procesamiento de la información audiovisual en la televisión local es un área que ha sido poco abordada desde la producción científica. Existe en el orden metodológico una escasez de herramientas e instrumentos que permitan diagnosticar el procesamiento de la información audiovisual en la televisión local. Existen técnicas y procedimientos específicos que permiten el procesamiento de la información, pero que se limitan a los procesos técnicos documentales tradicionales: clasificación, catalogación, indización y resumen. La televisión local por sus características requiere de medios y modelos específicos que permitan diagnosticar el procesamiento de la información audiovisual de los materiales que producen.; Audiovisual archives in local television stations favor the processing and preservation of audio-visual information for his retrival. The peculiarities of the processing of audiovisual information on local television stations archives have been little addressed from the scientific production. In the methodological order, there is a shortage of tools and instruments that allow diagnosing the processing of audiovisual information on local television. There are specific techniques and procedures that allow the processing of information, but which are limited to the traditional technical documentary processes: classification, cataloging, indexing and abstracting. Due to its characteristics, local television stations requires specific media and models that allow diagnosing the processing of audiovisual information from the materials they produce