O Sol e a Lua são os astros mais acessíveis à observação quer pelas suas frequentes aparições no céu, quer pelos seus tamanhos aparentes pronunciados. Por essas razões, constituem-se em astros disponíveis ao estudo, atendendo aos cuidados necessários no caso de observações solares. Apesar disso, pouca ou nenhuma atenção é dada a eles pelos professores dos ensinos fundamental e médio deixando de utilizar observações que podem contribuir muito para o aprendizado e, ainda, despertar o interesse dos alunos pela ciência. Em particular o Sol, permite a exemplificação e a compreensão de diversos fenômenos estudados na física, na biologia, na geografia, na química assim como permite aplicações práticas da matemática geometria e trigonometria ministradas em sala de aula. Escolhemos levar aos professores e aos estudantes universitários um curso sobre astronomia e física solar abordando questões sobre o Sol algumas pouco discutidas nos livros, mesmo os de Astronomia com a finalidade de proporcionar material de aprendizado, estudo e discussão de temas da astronomia moderna. Neste curso básico, serão abordados: como se concluiu que o Sol é uma estrela; como foram determinados seus principais parâmetros físicos e astronômicos tais como a sua distância, o seu tamanho, a sua massa, sua temperatura e composição química, e sua estrutura interna; e como o Sol produz energia. / The Moon and the Sun are the easiest celestial bodies to observe because their frequent appearance in the sky and their great apparent size. As a result, they are celestial bodies available to study, attending the essential cares regarding Sun observations. Nevertheless, teachers from elementary and high schools pay little or no attention to them and miss a great opportunity to use observations that might add a lot to the learning process and also to arouse students\' attention to science. The sun, specially, allows to illustrate and to understand several points that students learn in physics, biology, geography, and chemistry, and still can have practical applications in mathematics geometry and trigonometry taught in the classroom. We chose to bring to teachers and university students a course about astronomy and solar physics approaching issues of the Sun some of them very little discussed even in astronomy books for the purpose of provide learning material about modern astronomy topics. This basic course will develop: how was it concluded that the Sun is a star; how was it determined its main parameters, such as its distance, its size, its mass, its temperature and its chemical composition, and its internal structure; and how does the Sun produce energy.

Zheng, Shizhao = 聚合物太陽能電池的研究 / 鄭世昭. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Abstracts in English and Chinese. / Zheng, Shizhao = Ju he wu tai yang neng dian chi de yan jiu / Zheng Shizhao. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgements --- p.iv / Publications --- p.v / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Overview of solar cells --- p.1 / Chapter 1.2 --- Organic solar cells --- p.5 / Chapter 1.3 --- Device structure and working principles --- p.8 / Chapter 1.4 --- Device fabrication and characterizations --- p.13 / Chapter 1.5 --- Summary of chapter 1 --- p.22 / Chapter Chapter 2 --- Instrumentations and Experimental Procedures / Chapter 2.1 --- Introduction --- p.27 / Chapter 2.2 --- Instrumentations --- p.27 / Chapter 2.3 --- Experimental procedures --- p.33 / Chapter 2.4 --- Summary of chapter 2 --- p.38 / Chapter Chapter 3 --- Study of polymer solar cells device based on P3HT:PCBM / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- Effects of the choice of solvents and blending ratios --- p.42 / Chapter 3.3 --- Thermal annealing effect --- p.44 / Chapter 3.4 --- Effect of molecule weight and polydispersity --- p.48 / Chapter 3.5 --- Solvent soaking effect --- p.52 / Chapter 3.6 --- Summary of chapter 3 --- p.61 / Chapter Chapter 4 --- Study of polymer solar cell device based on new acceptor and new donor materials / Chapter 4.1 --- New acceptor material --- p.66 / Chapter 4.2 --- New donor materials --- p.73 / Chapter 4.3 --- Summary of chapter 4 --- p.81 / Chapter Chapter 5 --- Conclusions and future works / Chapter 5.1 --- Conclusions --- p.84 / Chapter 5.2 --- Future works --- p.86

Estágio realizado na Martifer ENER-Q e orientado pelo Doutor Pedro Correia Carvalho / Tese de mestrado integrado. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 2009

Tese de mestrado integrado. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 2009

Tese de mestrado. Faculdade de Engenharia. Universidade do Porto. 1998

The sun is a bountiful source of energy for our planet. .With the advent of photovoltaic cells, man has begun harnessing the sun's radiant energy, turning it into a form more directly useful: electricity. Commercially available solar cells currently operate at about 13% efficiency, sufficiently high to make them a viable source of electrical energy. It is of great interest, however, to improve their conversion efficiency, and to lower the cost of production so as to make them more economical, and thereby reduce our dependence upon traditional "dirty" sources of energy such as coal and oil. It has been found that an electrode coated with a thin film of nanocrystalline titanium dioxide, a very inexpensive and commonly available semiconductor, can be sensitized with a strong light-absorbing dye which can absorb the energy of sunlight and then transfer this energy as electronic charge into the electrode. A cell containing such an electrode is capable of producing a photocurrent at an appreciable voltage. The search is on to find the best sensitizing dye. It must absorb as much of the incident sunlight as possible, be capable of strong adsorption onto Ti02 so as to promote electron injection into the semiconductor, be relatively cheap and easy to synthesize, and be photochemically stable. It was the intent of this research to synthesize and test such a dye, a porphyrin dyad. The dyad was to be made from an electron donating moiety, meso-tetrakis(4-aminophenyl)porphyrin (TAPP), linked by an amide bond to an electron acceptor, meso-tetrakis(4-carboxyphenyl)porphyrin (TCPP). This material eluded attempts at synthesis, due to the poor reactivity of the aminoporphyrin and to the difficulty in ensuring that only one amide bond formed. Characterization of the monomers was carried out, and conditions for their chromatographic separation were determined. Recommendations for successful synthesis of the dyad are given.

1 / Bing Shan

The cost reductions and the environmental benefits aligned with global concerns about climate change have made solar photovoltaic technology the most installed source of energy in the power sector worldwide. Brazil has the largest know reserves of silicon in the world. Therefore, there is a huge potential for developing a national technology for purifying and manufacturing silicon wafers within an increasingly competitive and efficient photovoltaic industry. The IPEN initiative of investigating the production of metallic silicon and metallurgical route purification required a characterization of samples in different stages of production from quartz to wafer and understanding the characterization methods for silicon wafers taking into account the main defect mechanisms such as light-induced degradation. Metalic silicon is produced in IPEN via magnesiothermal reduction through acid leaching to form a metallurgical grade silicon with relatively low impurities. One more acid leaching step resulted in a specific ultra-metallurgical grade silicon. The same acid leaching was processed in a commercially available Brazilian-made metallurgical grade silicon produced via carbothermal reduction. All samples impurities was measured by ICP-OES. The result is a material with ultra-metallurgical grade silicon content with excess of B and P. While wafer characterization was studied, an extensive investigation was taken on LeTID, which causes remain unknown, at Institute for Energy Technology, Norway. Neighboring high performance mc-Si p-type wafers were tested in different firing process conditions. The effects was investigated in terms of defects activation and a corresponding lifetime degradation and recovery at illuminated annealing. A sample with almost fully suppressed LeTID is shown. A new method have been proposed to separate Boron Oxygen-Light Induced Degradation effects of LeTID, enabling to measure even where it was thought to be fully suppressed. New models for LeTID defect formation and suppression are proposed. Both silicon purification and light-induced degradation characterization in mc-Si studies shows a wide range of research on new production routes that may require tailored processes of crystallization and solar cell manufacturing such as gettering and firing. / As reduções de custos e benefícios ambientais alinhadas às preocupações globais com as mudanças climáticas tornaram a tecnologia solar fotovoltaica a fonte de energia mais instalada no setor de energia do mundo. O Brasil possui as maiores reservas conhecidas de silício. Portanto, existe um enorme potencial para o desenvolvimento de uma tecnologia nacional para purificação e fabricação de wafers de silício dentre a indústria fotovoltaica cada vez mais competitiva e eficiente. A iniciativa do IPEN de investigar a produção de silício metálico e a purificação de rotas metalúrgicas exigiu a caracterização de amostras em diferentes estágios de produção, do quartzo ao wafer e a compreensão dos métodos de caracterização dos wafers de silício, levando em consideração os principais mecanismos de defeitos, como a degradação induzida pela luz. O silício metálico é produzido no IPEN através da redução magnesiotérmica através da lixiviação ácida para formar um silício de grau metalúrgico com impurezas relativamente baixas. Mais uma etapa de lixiviação ácida resultou em um silício de grau ultra-metalúrgico específico. A mesma lixiviação foi feita em um silício de grau metalúrgico fabricado no Brasil, disponível comercialmente, produzido por redução carbotérmica. Todas as amostras foram medidas por ICP-OES. O resultado é um material com teores de silício de grau ultra-metalúrgico e excesso de B e P. Enquanto a caracterização do wafer foi estudada, uma extensa investigação foi realizada sobre o LeTID, que tem causas desconhecidas, no Institute for Energy Technology, Noruega. Os wafers vizinhos de mc-Si do tipo-p de alto desempenho foram testados em diferentes condições do processo de firing. Os efeitos foram investigados em termos de ativação de defeitos e uma correspondente degradação e recuperação no lifetime sob recozimento iluminado. Uma amostra com LeTID quase totalmente suprimido é mostrada. Um novo método foi proposto para separar os efeitos de Degradação Induzida por Luz relacionados ao Oxigênio e Boro do LeTID, permitindo até medir onde se pensava que estivesse totalmente suprimido. Novos modelos para formação e supressão de defeitos LeTID são propostos. Tanto a purificação de silício quanto a caracterização de degradação induzida pela luz nos estudos de mc-Si mostram uma ampla gama de pesquisas sobre novas rotas de produção que podem exigir processos personalizados de cristalização e fabricação de células solares, como gettering e firing.

No description available.

Many current technologies used in solar cell fabrication have been successfully adapted from the integrated circuits industry. The success of laser processing applications in this industry indicates that such techniques should be considered to reduce manufacturing costs and to improve electrical efficiency of solar cells. This thesis examines the application of advanced laser processing to improve the electrical performance and reduce manufacturing costs of solar cells. It focuses on several different aspects of laser processing; (1) understanding and characterising the effect of laser pulses on silicon, (2) developing new fabrication technologies and (3) integrating laser processes with working solar cell devices. The thesis begins with an overview of existing solar cell structures that incorporate laser processing. A study is then presented that explores the detrimental effects of laser processing, how it can be avoided and how to characterise its influence on solar cell electrical properties. Experimental results combine Yang defect etching, photoconductance decay measurements and a new technique of photoluminescence imaging to isolate the influence of laser ablation and laser melting on silicon wafers. This understanding is used in the development of several laser processes. A laser texturing technique is developed to texture the surface of multicrystalline wafers that cannot be effectively textured with the alkaline etches used on single crystal material. Three advanced laser contacting schemes; laser micro contacts, laser defined aluminium electrodes and laser doping, are assessed as techniques to improve cell efficiency and to reduce fabrication costs. In the final chapter the integration of laser processing with solar cell devices is demonstrated through the fabrication and characterisation of n-type double-sided solar cells with laser doped contacts. Efficiencies of up to 17.4% with an open circuit voltage of 672 mV are reported. This thesis also presents the application of a new characterisation technique, based on photoluminescence, to aid in improving both new and existing fabrication technologies. The work presented in this thesis demonstrates the applicability of advanced laser processing to solar cell fabrication and shows how laser processes can be used in a variety of ways to improve the electrical performance and reduce the fabrication complexity of solar cell devices.