Iron based dyes promise cheaper solar energy applications

October 14, 2015 // By Paul Buckley
Researchers at Lund University in Sweden have found a way to capture energy from sunlight by using molecules that contain iron which could be used to develop efficient and environmentally friendly solar energy applications.

The results are presented in the latest issue of Nature Chemistry.

The Lund researchers are working on solar cells consisting of a thin film of nanostructured titanium dioxide and a dye that captures solar energy. Today, the best solar cells of this type use dyes containing ruthenium metal – a rare and expensive element.

“Many researchers have tried to replace ruthenium with iron, but without success. All previous attempts have resulted in molecules that convert light energy into heat instead of electrons, which is required for solar cells to generate electricity,” explained Villy Sundström, Professor of Chemical Physics at Lund University.

Researchers at the Chemistry Department in Lund, in collaboration with Uppsala University, have successfully produced an iron-based dye that is capable of converting light into electrons with nearly 100 per cent efficiency.

“The advantage of using iron is that it is a common element in nature. It can provide inexpensive and environmentally friendly applications of solar energy in the future,” said Kenneth Wärnmark, Professor of Organic Chemistry at Lund University.

By combining the experiments with advanced computer simulations, the researchers are able to understand in detail required design concepts for the iron molecules to work. This knowledge is now being used for further developing the iron-based dyes. More research is needed before the new solar cell dye can be used in practice, but there are high hopes.

“The results of the study suggest that solar cells based on these materials can be at least as effective as those of today that are based on ruthenium or other rare metals,” claimed Sundström.

The discovery could also advance research on solar fuels in which, like in photosynthesis of plants, water and carbon dioxide are turned into energy-rich molecules – solar fuel – with the help of sunlight.