A simple experiment for the preparation of transparent conducting glass electrodes by deposition of pure and fluorine doped SnO2 films is described. This procedure was tested in the undergraduate inorganic course at IQ-UNICAMP. The success in achieving a conducting layer was easily checked using the standard probes of a volt-ohm meter. The optical transmittance and thickness were studied by UV-vis spectrophotometry. To discuss the experimental results we place significant emphasis on molecular orbital and energy band model theories. The undergraduate students can also discuss the concepts related to the electronic properties of solids and to interesting new materials, such as transparent conducting films, which are the subject of significant current research and technological applications.

As células solares de TiO2/corante são uma alternativa promissora para o desenvolvimento de uma nova geração de dispositivos fotovoltaicos. Estas células resultam de uma bem sucedida combinação de materiais: um eletrodo transparente revestido com um filme poroso de partículas nanocristalinas de TiO2 sensibilizadas com um corante, um eletrólito contendo um par redox adequado e um contra-eletrodo revestido com platina. Em geral, utilizam-se complexos bipiridínicos de Ru como corantes fotosensibilizadores. O desempenho da célula na conversão de luz em eletricidade depende dos níveis de energia do semicondutor e do corante, e da cinética dos processos de transferência de elétrons na interface semicondutor | eletrólito. Esta revisão apresenta uma discussão da influência de cada um dos materiais que constituem as células solares de TiO2/corante no processo de conversão de energia, com ênfase aos resultados obtidos para células solares de estado sólido, preparadas com um eletrólito polimérico.

Dye-sensitized TiO2 solar cells, DSSC, are a promising alternative for the development of a new generation of photovoltaic devices. DSSC are a successful combination of materials, consisting of a transparent electrode coated with a dye-sensitized mesoporous film of nanocrystalline particles of TiO2, an electrolyte containing a suitable redox-couple and a Pt coated counter-electrode. In general, Ru bipyridyl complexes are used as the dye sensitizers. The light-to-energy conversion performance of the cell depends on the relative energy levels of the semiconductor and dye and on the kinetics of the electron-transfer processes at the sensitized semiconductor | electrolyte interface. The rate of these processes depends on the properties of its components. This contribution presents a discussion on the influence of each of the materials which constitute the DSSC of the overall process for energy conversion. An overview of the results obtained for solid-state dye-sensitized TiO2 solar cells assembled with polymer electrolytes is also presented.