Browsing all articles tagged with sol-gel synthesis

New prospects for solar cells

new solar cellsThe most efficient solar cells, composed of a semiconductor material such as silicon, have been developed in Switzerland in the early 90s. As in the case of conventional electrochemical batteries, solar cells consist of a cathode, a platinum-based catalyst, and an anode, a porous layer formed from titanium dioxide nanoparticles and coated with a dye absorbs sunlight. A conductive liquid, the electrolyte is placed between two electrodes.

Despite the use of materials for the most inexpensive, easy to manufacture and flexible, large-scale commercialization of these batteries confronts two major obstacles. The electrolyte is very corrosive, causing a deficiency in sustainability. It is also very colorful, preventing light from entering and effectively limiting the photo-voltage of 0.7 volts. Moreover, platinum is an expensive material, non-transparent and rare.

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ZnO nanostructures


ZnO nanostructureNanotechnology and nanoscience have certainly been one of the most popular fields of research in the last decade. Manufacturing processes are now able to carry out the deterministic synthesis of nanostructures with properties radically different from their macroscopic forms, enabling the realization of previously unthinkable devices. Despite these advances, few nanofabrication techniques feature the required characteristics for the commercial manufacturing of these new products in an effective fashion since they are either too slow, or too expensive and complex.

This page is a summary of my doctoral thesis project, accomplished at the Laboratory for multiscale mechanics at the École Polytechnique de Montréal (LM2, mechanical engineering). The main objective of this project was to develop a new manufacturing technique allowing the local synthesis of nanostructures on a surface for their eventual integration into nanodevices. The desired process has to be selective, reproducible, versatile, simple, fast and inexpensive for potential industrial utilization. Moreover, the manufacturing process must have a minimal environmental impact for sustainable development.

To implement the required specifications, a laser process combining the characteristics of laser-induced chemical liquid deposition (LCLD) and of sol-gel synthesis was proposed. The technique is very simple and consists of three steps. A precursor solution is first prepared. Next, a droplet of a controlled volume is transferred on a substrate by means of a micropipette. The droplet is then irradiated using a laser emitting in the infrared to induce the fast synthesis of nanostructures.

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