Abstract: La fabricación de las celdas fotovoltaicas inorgánicas son aquellas cuyo semiconductor es a base de material inorgánico (Si, AsGa, CuInS2, CIS, CdTe), son poco económicas, por ende, es necesario hallar una manera de producir celdas solares sin que la inversión económica sea costosa. Debido a esta dificultad tecnológica, se ha optado por usar semiconductores orgánicos en la fabricación de las celdas. Los paneles solares orgánicos no se contemplan como un sustituto a los de silicio como material semiconductor, sino un complemento para crear mejores fuentes de energía. En este caso, se plantea el uso de los nanotubos de carbono (CNT) como material semiconductor en la fabricación de celdas fotovoltaicas orgánicas.

Resumen: Las aplicaciones de la electrónica exigen mayor eficiencia de los dispositivos electrónicos que se utilizan hoy en día. Entre los aspectos mas importantes esta el área ocupada por un circuito: Se busca que los dispositivos electrónicos ocupen el menor espacio posible. La tecnología que se utiliza hoy en día para fabricar dispositivos semiconductores está llegando a un punto limite, donde cada vez es mas difícil obtener reducción en el tamaño sin afectar otras características del dispositivo. La nanoelectrónica está evolucionando a un punto donde se hace posible la construcción de dispositivos semiconductores que presenten mejores características que los fabricados en la actualidad. Este documento muestra una revisión bibliográfica sobre nanotecnología, con el fin de presentar una propuesta de investigación para implementar transistores basados en nanotubos de carbono. Este trabajo está en su fase inicial, se espera que a finales del 2009 se tenga una metodología de implementación de transistores utilizando nanotecnología.

Resumo: Após décadas das primeiras publicações sobre a plasticidade transcricional do sistema digestivo dos insetos polífagos, ainda não se conhece em profundidade como os genes são regulados e as vias de sinalização envolvidas neste mecanismo adaptativo. Inicialmente, foi mostrado que a adaptação de lagartas de H. armigera à alimentação com inibidores de peptidase de soja (IPs) se deve à alteração do perfil transcricional de genes codificadores de serino peptidases do sistema digestivo. A presença dos IPs na dieta causou mudanças na regulação de genes de um amplo repertório de enzimas proteolíticas, principalmente com o aumento de genes de tripsinas. A regulação diferencial de enzimas digestivas foi associada à adaptação da H. armigera ao efeito anti-nutricional dos IPs. Além disso, a análise de dados de expressão gênica em larga escala (RNA-seq) mostrou que aproximadamente 40% dos transcritos (cerca de 500 epialelos potenciais) induzidos pelos IPs foram transmitidos à geração seguinte, apesar das lagartas desenvolverem-se em dietas desprovidas de IPs. A fim de caracterizar um possível mecanismo epigenético responsável por este mecanismo adaptativo, foi realizado o metiloma do sistema digestivo das lagartas da primeira geração (alimentadas com e sem IPs) e das progênies de lagartas expostas aos IPs. Epialelos de metilação do DNA foram associados aos controles transcricional e traducional, sugerindo um possível envolvimento da alteração do padrão de metilação na adaptação de H. armigera aos IPs. Este trabalho abre novas perspectivas no entendimento do polifagismo e a plasticidade dos insetos na alimentação de um amplo número de plantas hospedeiras, influenciando o seu curso evolutivo.

Abstract: The history of Colombia has been defined by the paradox of the coexistence of violence and economic growth. While the economy of the country has grown almost uninterruptedly since the middle of the 20th century, in 2019 the state was still not fully capable of reasserting its presence nor of providing justice or security for all of its citizens across its territory. This chapter analyses the paradox of the coexistence of armed violence and economic growth in Colombia, in which parts of the elite sections of the country benefit by the lack of security and justice. Violence is good for business, although not good for statehood.

Abstract: For the first time a comprehensive life cycle assessment (LCA) is reported of a large-area perovskite/Si tandem photovoltaic (PV) module of about 2 m², with an assumed power conversion efficiency of 30%, 30 years lifetime and an annual degradation of 0.5%, manufactured in a 1 GW production plant. By means of the LCA method, we calculate the contribution to the International Reference Life Cycle Data System (ILCD) impact categories associated with a perovskite/Si tandem PV system compared with a passivated emitter and rear cell (PERC) used as reference. We consider a functional unit of 1 kWh of generated direct current electrical energy from the tandem module over its lifetime. It was found that the most significant environmental hotspots are the silicon wafer production and the balance of system (BOS), especially the mounting system, inverter and electric installation. Overall, the impact contributions to the environment caused by the perovskite sub-module are below 1% throughout all the ILCD categories in focus: climate change, freshwater ecotoxicity, water resource depletion and human toxicity. Even the contribution of lead to human toxicity is just about 0.01%. For all the impacts assessed, the perovskite/Si tandem shows a decrease of between 17-20% of the contributions to each impact category compared to the PERC-module based reference PV system, if the Si bottom sub-module has an initial cell efficiency of at least 22% with 1% cell-to-module (CTM) loss, and the perovskite top sub-module has a minimum initial cell efficiency of 18% with at most 5% CTM loss and a transmittance near IR region larger than 80%. The key result found in this work is the relevance of the performance and reliability of the PV system to achieve lower environmental impacts. A comparison between optimistic, realistic, and pessimistic scenarios was performed to investigate this matter: in the worst-case scenario, the environmental impact of the PV tandem system would have a general 50% increase throughout all ILCD impact categories against the realistic case, whereas in the optimistic one, the results suggest a reduction of 46% to the global impact contributions, compared to the realistic scenario.

Diluting organic molecules in a polymer matrix material suppresses non-radiative behavior, leading to biluminescence, wherein light is emitted efficiently from both singlet and triplet states. In summary, biluminescence has developed into a thoroughly optimized and unique emissive system. Among the characteristics obtained through this system, the most significant is the ability of biluminophores to offer direct access to the radiative states of both spin manifolds (singlets and triplets) in organic molecules without the requirement for special or complex material combinations. As a result, an exciton is given the chance to re-emit its energy, regardless of its initial state. In future work, we intend to increase the toolset of organic biluminophores by screening materials to determine the structure-property relationships behind persistent phosphorescence, and to identify molecular building blocks that are suitable for the development of future materials. In addition, we will intensify our exploration of biluminescence for future applications (e.g., sensing).

Abstract: Biluminescent organic emitters show simultaneous fluorescence and phosphorescence at room temperature. So far, the optimization of the room-temperature phosphorescence in these materials has drawn the attention of research. However, the continuous-wave operation of these emitters will consequently turn them into systems with vastly imbalanced singlet and triplet populations, which is due to the respective excited-state lifetimes. This study reports on the exciton dynamics of the biluminophore NPB (N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1-biphenyl)-4,4-diamine). In the extreme case, the singlet and triplet exciton lifetimes stretch from 3 ns to 300 ms, respectively. Through sample engineering and oxygen quenching experiments, the triplet exciton density can be controlled over several orders of magnitude, allowing us to study exciton interactions between singlet and triplet manifolds. The results show that singlet−triplet annihilation reduces the overall biluminescence efficiency already at moderate excitation levels. Additionally, the presented system represents an illustrative role model to study excitonic effects in organic materials.

Abstract: The property of an organic molecule able to emit light efficiently from both their singlet and triplet excited states is called biluminescence. This dual state emission, particularly at room temperature, is difficult to achieve by purely organic molecules. It is possible only if the competitive thermal decay is suppressed effectively, enhancing the yield from the triplet state (i.e. phosphorescence) in addition to the conventional fluorescence. Biluminescence was identified in a simple host:guest system in which the biluminophore (i.e. an organic molecule showing biluminescence) NPB [N,N’-di(naphtha-1-yl)-N,N’- diphenyl-benzidine] is embedded in a rigid matrix, for example, the polymer PMMA [poly(methyl methacrylate)]. This system is unique not only due to the dual state emission, having fluorescence and phosphorescence emissions at 425nm and 530nm, respectively, but also because the large range of exciton lifetimes is extended up to nine orders of magnitude between nanosecond fluorescence and second phosphorescence. Up to date, efforts have been placed exclusively in the research of room temperature phosphorescence (RTP), although fluorescence can be observed from these systems as well. Therefore, the aim of this thesis was the investigation of the fundamental photophysical processes and characteristics of biluminescent organic molecules, in addition to their usage in promising applications as it will be described next. For instance, the most used approach for oxygen sensing is based on quenching of luminescent excited states, following a scheme of optical monitoring, i.e. correlating luminescence over-time data with oxygen concentrations. However, regardless whether one pursues fluorescence or phosphorescence quenching, they share a common drawback: They cannot monitor the effect of sample degradation due to extensive light exposure. In fact, one cannot distinguish between oxygen having penetrated the film and quenched the luminescence, or the sample being degraded over time due to e.g. photobleaching of the emitting molecules. The former represents an issue, especially for build-in applications. Now herein, it was proposed to use biluminescence to exclude degradation processes from oxygen sensing data evaluation, through a simple fluorescence-to-phosphorescence intensity ratio. This can be achieved, because it was proven here that the fluorescence is not directly quenched by oxygen, whereas the long-lived RTP is sensitive to it. Therefore, the fluorescence acts as self-referencing in a biluminescent sensor, which serves as an alternative solution to monitor oxygen concentrations. Additionally, the integration of the sensor into optoelectronic devices is considered as a potential future direction. Furthermore, it was revealed in this thesis that the difference in exciton lifetime yields to a significant limitation of luminescence efficiency, because of exciton accumulation under continuous illumination, causing bimolecular processes like singlet-triplet and triplet-triplet annihilation (STA and TTA, respectively), as well as optical saturation. All those processes occur already at moderate excitation intensities. It was demonstrated through sample engineering and oxygen quenching experiments, that the triplet exciton density can be controlled over several orders of magnitude, allowing to study exciton interactions between singlet and triplet manifolds. Consequently, the presented biluminescent system represents an illustrative role model to study excitonic effects in organic molecules. For example, in organic light-emitting diode materials, where the aforementioned effects i.e. STA, TTA and saturation, are application relevant but much more difficult to investigate. Mainly because light emission can be observed only from one state, instead of both states like in biluminescence.

Abstract: Every year, thousands are selectively killed and displaced in social cleansing campaigns in Colombia announced in publicly-posted pamphlets. Also known as the “black hand”, the selective killings have become a hallmark of the country’s poorest neighborhoods. Often perpetrated by neighbors, under the auspices of paramilitary groups and with the complicity or even participation of local police, these murders are touted as the necessary procedures of order in places where official justice cannot reach. Drug users, petty criminals, LGBTQ folk and especially trans women, are the preeminent targets of such campaigns. Already largely labeled as deviant or marginal, those whose lives are threatened and who dare make official complaints are dismissed by those institutions tasked with their safety. Purgare invites a consideration of social cleansing not from the perspective of the violence of its perpetrators, but through those who stand in resistance against it. This project accompanies a group of trans women who, faced with the extra-legal and legal dismissal of their lives, take recourse to magic to protect themselves and to reassert a modicum of agency. Bringing together photojournalism, anthropology, and artistic representation, the series and essay inhabits the magically real space created by these women, illuminating the powers they conjure in the worlds they create. Purgare stages the journeys of transformation crafted by these self-styled witches through their manipulations of plants and energies to forge lasting and powerful connections between new peoples and novel worlds. Purgare is imagined between disciplines and knowledges in an effort to expand the bounds of story-telling traditionally produced about violence. It builds a space in which those who struggle against structural violence can meet to create new representations of themselves and together weave novel images of power and possibility. Based on the stories of Stefania Grajales, Paola Caicedo and Catalina Lozano.

Abstract: Las Malinches vs the Great Social Network’ is a visual album by a Colombian music band, specially put together for this graduation project. The soundtrack narrates the group’s formation process, in response to the connectivity programs introduced by Facebook in the global south. The album portrays the band’s state of paralysis in the face of these connectivity programs. Finally, the album celebrates existing communication systems that could present a less corporate alternative to the American platform. The album contains videos that contextualize and satirize Facebook’s charitable endeavors and additionally, it includes original music that acts as counter narrative to Zuckerberg’s neoliberal and possibly neocolonial gospel. The electro-cumbia songs, written specifically for this graduation project, question the inevitable position of Facebook. They mix local rhythms with western sounds and thus propose a new musical language in which both influences merge. Orality is used as a tool for knowledge creation, a fundamental practice in South American cultures. The visual album is distributed by means of a raspberry pi, aiming to show the public that there are alternatives to share content in hybrid spaces where physicality is as important as digital connectivity. This allows us to think about the ‘internet outside the internet’. It works as the starting point for the creation of community networks that, in the end, demonstrate how the narratives of the large tech-companies might be forceful, but they are certainly not inevitable. Resumen: ‘Las Malinches vs the Great Social Network’ es un álbum visual de una banda de música colombiana, elaborado especialmente para este proyecto de graduación. La banda sonora narra el proceso de formación del grupo, en respuesta a los programas de conectividad introducidos por Facebook en el sur global. El álbum retrata el estado de parálisis de la banda frente a estos programas de conectividad. Finalmente, el álbum celebra los sistemas de comunicación existentes que podrían presentar una alternativa menos corporativa a los de la plataforma estadounidense. El álbum contiene videos que contextualizan y satirizan los esfuerzos caritativos de Facebook y, además, incluye música original que actúa como contranarrativa del evangelio neoliberal y posiblemente neocolonial de Zuckerberg. Las canciones de electro-cumbia, escritas específicamente para este proyecto de graduación, cuestionan la inevitable posición de Facebook. Mezclan ritmos locales con sonidos occidentales y así, proponen un nuevo lenguaje musical en el que se fusionan ambas influencias. La oralidad se utiliza como herramienta para la creación de conocimiento, retomando esta práctica fundamental de las culturas sudamericanas. El álbum visual se distribuye mediante una raspberry pi, con el objetivo de mostrar al público que existen alternativas para compartir contenidos en espacios híbridos donde la fisicalidad es tan importante como la conectividad digital. Esto nos permite pensar en "Internet fuera del Internet". El proyecto funciona entonces como el punto de partida para la creación de redes comunitarias que, al final, demuestran cómo las narrativas de las grandes empresas tecnológicas pueden ser poderosas, pero ciertamente no son inevitables.