Dye Sensitized Solar Cells (DSSC)

BASF.com /Press Release / October 11th 2007
http://www.corporate.basf.com/en/sustainability/
presse/pm.htm?pmid=2869&id=V00-ZQ-_9BzcJbcp.mB

- Advances in photovoltaics: Ionic Liquids for new class of solar cells
- Partnership to develop new formulations for increased efficiency of solar technology

G24 Innovations Limited (G24i) and BASF have today (October 11th, 2007) announced a joint development agreement. The two companies will initiate a program to develop ionic liquids and formulations that further improve both performance and efficiency of G24i’s solar cells using a proprietary DYE-SENSITIZED THIN FILM technology.

The photovoltaic cells produced by G24i are sensitive to far more of the visible spectrum of light than conventional solar cells, so that all sorts of light sources can be used to generate power, even at relatively low levels of light intensity. The photovoltaic process used is roughly similar to photosynthesis in plants: a special ruthenium dye assumes the role of chlorophyll, turning light into electrical energy in a chemical process. Specifically adapted to the electrode and dye system, the ionic liquids are key to ensuring that the solar cell will generate power in a reliable and stable manner.

G24i’s DYE-SENSITIZED THIN FILM technology is based on solar cells originally developed by Dr. Michael Graetzel of the Swiss Institute of Technology (Ecole Polytechnique Fédérale de Lausanne (EPFL). Solar cells and products developed using this technology are lightweight, durable and ideal for integration or embedding into a wide range of products. G24i is developing solar products to power a range of portable electronics such as mobile telephones but also examines the use in smart textiles and building-integrated materials.

BASF is manufacturing ionic liquids - salts which are liquid below 100°C – that are suitable for use across a broad range of different applications ranging from processing chemicals and polymers, to engineering liquids like hydraulic liquids or lubricants, to uses in electro-chemistry.

Clemens Betzel, President of G24i comments: “BASF’s knowledge and experience in the field of chemicals, coupled with G24i’s specific research and development capabilities will together make a huge impact on the level of innovation which can be achieved.” He continues: “G24i’s product represents a technological breakthrough that will make solar energy a viable renewable energy option for the first time for a range of new industries and geographies. Whilst BASF has been a supplier of ionic liquids to G24i for some time, this new agreement will allow us to work more closely on the selection of suitable liquids and formulations that we will test at our specialist facility. We will share the results of these tests and work with BASF to continuously enhance the quality of our product.”

“We are enthusiastic about G24i’s technology, as they are the first company in the world to produce this new class of solar cells at an industrial scale, and we are bringing our research and development expertise in ionic liquids into our cooperation,” said Dr. Walter Gramlich, President of BASF’s operating division Intermediates.

BASF looks back on some six years of experience in the fairly recent field of ionic liquids, both in manufacturing these materials and in their full-scale industrial use. At its Ludwigshafen site, the company runs the first large-scale industrial process worldwide that uses ionic liquids. This process allows fast and simple removal of acids from reaction mixtures. The reaction of an acid with a base results in a liquid salt instead of solid crystals, which frequently cause process problems in production. Reliance on ionic liquids does away with time-consuming and expensive filtration. These liquids can be easily separated from the desired products, like oil from water, and can also be reused. 1?Methylimidazole, which replaces other bases used as additives, additionally acts as a catalyst, thus speeding up the reaction considerably.