Breakthrough in research for the production of solar cells efficient and inexpensive.

On April 6, 2010 – With two technologies developed by the team of Professor Benoît Marsan Department of Chemistry, University of Quebec at Montreal (UQAM), the future of both scientific and commercial solar cells could be transformed at all everything! Indeed, he managed to solve two problems for over 20 years, holding back the development of solar cells both efficient and affordable. The results of the research have been published in prestigious scientific journals Journal of the American Chemical Society (JACS) Nature and Chemistry.

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Solar energy: a huge untapped potential
The Earth receives more solar energy in one hour than the planet than is consumed in a year now! Unfortunately, despite this huge potential, solar energy is not used. In fact, electricity produced by conventional solar cells composed of semiconductor materials like silicon, costs 5 or 6 times higher than from traditional sources of energy such as fossil fuels or hydropower. Over the years, many research teams are harnessed to the task of developing a solar cell, could be both effective in terms of energy and inexpensive to produce.

The solar cell sensitized by a dye
One of the most promising solar cell was designed in the early
90s by Professor Michael Graetzel of Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland. Guided by the principle of photosynthesis, biochemical process that allows plants to feed themselves by eating light energy, the Graetzel solar cell is composed of a porous layer of nanoparticles formed from a white pigment, the titanium dioxide, covered with a molecular dye which absorbs sunlight, like the chlorophyll in green leaves. The coated titanium dioxide pigment is immersed in an electrolyte solution. A platinum-based catalyst completes the package.

We can say that, as in the case of a conventional electrochemical cell (such as alkaline batteries), two electrodes (the anode of titanium dioxide and platinum cathode in the case of the Graetzel cell) are placed around a conductive liquid (electrolyte). The sun’s rays pass through the cathode and the electrolyte, and then extract electrons at the anode of titanium dioxide, a semiconductor at the bottom of the stack. These electrons travel through a wire, the anode to the cathode, creating an electrical current. Thus the sun’s energy is converted into electricity.

Most materials used to make this stack are inexpensive, easy to manufacture and flexible, allowing them to integrate all kinds of objects or materials. In theory the Graetzel solar cell is very interesting. Unfortunately, despite the design quality of this battery, two major problems still prevent the large-scale commercialization:

  • the electrolyte is (1) very corrosive, causing a lack of sustainability, (2) very colorful, which prevents light from passing efficiently and (3) limits the photo-voltage of 0.7 volts;

  • the cathode is covered with platinum, an expensive material, non-transparent and rare.

Despite numerous attempts, until the recent contribution of Professor Marsan, no one could find a real solution to these problems!

The solutions of Professor Marsan
Professor Marsan and his team for several years to design an electrochemical solar cell. His work has led to use novel technologies, for which he received many patents. Thinking about the problems of battery developed by his Swiss colleague, Professor Marsan realized that two of the technologies developed for the electrochemical cell may also apply to the Graetzel solar cell, either:

  • for the electrolyte, the creation of any new laboratory molecules whose concentration could be increased through the contribution of Professor Livain Breau, also of the Chemistry Department. The liquid or gel that results is transparent, non-corrosive and can increase the photo-voltage, which improves performance and stability of the stack.

  • and replacement of platinum with cobalt sulfide to produce the cathode. This material is much less expensive than platinum. It is also more efficient, more stable and easier to produce in the laboratory.

As soon published in the journals Nature and Chemistry JACS, these proposals have generated enthusiasm in scientific circles, whereas this number contribution of Professor Marsan as a major breakthrough in research for the production of solar cells that are both efficient and inexpensive.

Source: University of Quebec at Montreal

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