Solar Cells: UQAM researcher solves two 20-year-old problems

Professor Marsan has come up with solutions for two problems that, for the last twenty years, have been hampering the development of efficient and affordable solar cells. His findings have been published in two prestigious scientific journals, the Journal of the American Chemical Society (JACS) and Nature Chemistry.

The untapped potential of solar energy
The Earth receives more solar energy in one hour than the entire planet currently consumes in a year! Unfortunately, despite this enormous potential, solar energy is barely exploited. The electricity produced by conventional solar cells, composed of semiconductor materials like silicon, is 5 or 6 times more expensive than from traditional energy sources, such as fossil fuels or hydropower. Over the years, numerous research teams have attempted to develop a solar cell that would be both efficient in terms of energy and inexpensive to produce.
Dye-sensitized solar cells
One of the most promising solar cells was designed in the early '90s by Professor Michael Graetzel of the Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland. Based on the principle of photosynthesis—the biochemical process by which plants convert light energy into carbohydrate (sugar, their food)—the Graetzel solar cell is composed of a porous layer of nanoparticles of a white pigment, titanium dioxide, covered with a molecular dye that absorbs sunlight, like the chlorophyll in green leaves. The pigment-coated titanium dioxide is immersed in an electrolyte solution, and a platinum-based catalyst completes the package.

As in a conventional electrochemical cell (such as an alkaline battery), two electrodes (the titanium dioxide anode and the platinum cathode in the Graetzel cell) are placed on either side of a liquid conductor (the electrolyte). Sunlight passes through the cathode and the electrolyte, and then withdraws electrons from the titanium dioxide anode, a semiconductor at the bottom of the cell. These electrons travel through a wire from the anode to the cathode, creating an electrical current. In this way, energy from the sun is converted into electricity.

Most of the materials used to make this cell are low-cost, easy to manufacture and flexible, allowing them to be integrated into a wide variety of objects and materials. In theory, the Graetzel solar cell has tremendous possibilities. Unfortunately, despite the excellence of the concept, this type of cell has two major problems that have prevented its large-scale commercialisation:

The electrolyte is: a) extremely corrosive, resulting in a lack of durability; b) densely coloured, preventing the efficient passage of light; and c) limits the device photovoltage to 0.7 volts.

The cathode is covered with platinum, a material that is expensive, non-transparent and rare. Despite numerous attempts, until Professor Marsan's recent contribution, no one had been able to find a satisfactory solution to these problems.

Professor Marsan's solutions
Professor Marsan and his team have been working for several years on the design of an electrochemical solar cell. His work has involved novel technologies, for which he has received numerous patents. In considering the problems of the cell developed by his Swiss colleague, Professor Marsan realized that two of the technologies developed for the electrochemical cell could also be applied to the Graetzel solar cell, specifically:
For the electrolyte, entirely new molecules have been created in the laboratory whose concentration has been increased through the contribution of Professor Livain Breau, also of the Chemistry Department. The resulting liquid or gel is transparent and non-corrosive and can increase the photovoltage, thus improving the cell's output and stability.
For the cathode, the platinum can be replaced by cobalt sulphide, which is far less expensive. It is also more efficient, more stable and easier to produce in the laboratory.

Immediately following their publication in JACS and Nature Chemistry, Professor Marsan's proposals were received enthusiastically by the scientific community. Many view his contribution as a major research breakthrough on the production of low-cost and efficient solar cells.

Links to the articles in JACS and Nature Chemistry:
http://pubs.acs.org/doi/abs/10.1021/ja905970y
http://www.nature.com/nchem/journal/vaop/ncurrent/abs/nchem.610.html
Version française:
http://www.salledepresse.uqam.ca/communiques-de-presse-2010/147-recherche-piles-solaires.html

Information:
Professor Benoît Marsan
Department of Chemistry
Université du Québec à Montréal
Phone: 514 987-3000, ext. 7980
Email: marsan.benoit@uqam.ca
Source: Claire Bouchard, Press Relations Officer
Phone: 514 987-3000, ext. 2248
Email: bouchard.claire@uqam.ca

Media Contact

Claire Bouchard EurekAlert!

More Information:

http://www.uqam.ca

All latest news from the category: Life Sciences and Chemistry

Articles and reports from the Life Sciences and chemistry area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Back to home

Comments (0)

Write a comment

Newest articles

Results for control of pollutants in water

Brazilian scientists tested a simple and sustainable method for monitoring and degrading a mixture of polycyclic aromatic hydrocarbons, compounds present in fossil fuels and industrial waste. An article published in the journal Catalysis…

A tandem approach for better solar cells

Perovskite-based solar cells were first proved in 2009 to have excellent light-absorbing properties of methylammonium lead bromide and methylammonium lead iodide, collectively referred to as lead halide perovskites or, more…

The behavior of ant queens is shaped by their social environment

Specialization of ant queens as mere egg-layers is reversible / Queen behavioral specialization is initiated and maintained by the presence of workers. The queens in colonies of social insects, such…

Partners & Sponsors