Francisco Nivaldo Aguiar Freire

Deposition by Spray-Pyrolysis of Tin Oxide Doped with Fluorine Produced by Sol-Gel Method

Solar energy is one of the most important sources of renewable energy today. The production of electric energy is based on silicon cells, which are expensive and difficult to produce and therefore, New preparation methods, materials or approaches are needed. This work aims to deposit Tin oxide doped with fluorine, prepared by sol-gel, on a glass substrate using the spray pyrolysis technique. F-SnO2 (FTO) solution was synthesized by sol-gel method, employing NH4F and SnCl2 precursors in an ethanol solution. Before the formation of the gel, the solution was sprayed using a pistol aerographic, On a substrate at approximately 600oC. This process was repeated 50 times, and after that, the sample was cooled until room temperature inside the furnace. The obtained samples (substrates for the PV cell) present a resistance between 10 and 30 Ω. The energy dispersive x-ray (EDS) was used to confirm the presence of fluorine in the SnO2 network.

Modelo teórico relacionando as potências elétrica e química em célula fotossensibilizada com corante

This paper presents a theoretical model relating the electrical power to the chemical power in a photosensitized dye-cell. The same is based on the junction of present concepts of chemical potential models and chemical power. Thus, from these two considerations is possible to perform tests under various physical and environmental conditions during the solar conversion process. Consequently, the proposed theoretical model allows relating the power to solar chemical parameters: solid angle, temperature of the radiation source, wavelength and temperature of the photosensitized dye-cell. The electrons flow generation within the cell is promoted by absorption of solar energy incident on the dye. Therefore, the main condition embodied in this work is based on the incident energy absorption surface is the dye.

Caracterização da eletrodeposição de filmes finos de CdTe sobre Pt em meio ácido

The electrodeposition has been used for obtaining semiconductor materials; however, remain unclear the mechanisms involved in this process. Thus, this paper presents the research of this process, showing the characterization of electrodeposited CdTe on platinum substrate in acid solution. The deposition occurs from 0.0 V relative to the electrode Ag/AgCl KClsat with step activated control and diffusion. The thin film of CdTe was electrodeposited on the platinum substrate at room temperature (~ 24 ° C) from an acidic solution. The influence of the applied potential was investigated using surface characterization techniques such as X-ray diffraction analyses and scanning electron microscopy. The electrical properties of the films were performed capacitance measurements (Mott-Schottky plot). The thin CdTe films presented the prominent (220) planes, showing have a preferential growth in that plane. The films show a granular morphology influenced by deposition potential and property of an n-type semiconductor.