The problem with iron solar cells…

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Researchers at Lund University in Sweden have been working with an iron based molecule they say could provide a low cost alternative to solar cells made from rarer materials.

To better understand the light absorbing and charge carrying behavior of the iron n-heterocyclic carbene complex they developed, the group headed to Stanford University in the U.S. to perform experiments with a free electron laser.

The results are published in Angewandte Chemie. The group observed two pathways by which molecules excited by light returned to their ‘ground state’ before a charge could be extracted and found around 30% of the molecules return to lower activity states in around 150 femtoseconds, via a process of ‘ultrafast relaxation’.

“It was shown that in one-third of cases, the electron is not held in position long enough for us to extract the energy,” said Jens Uhlig, chemistry researcher at Lund University and leader of the study. “Instead the energy disappeared very rapidly over a previously unknown channel.”

Closing the loophole

Identifying that channel enabled the group to begin working on ways to close the loophole to prevent the loss from occurring. A Lund University statement said it is planning to conduct further studies using major research facilities such as Stanford’s laser and the MAX IV synchrotron facility in Lund.

“If we can find a way to extract energy from all the molecules, the efficiency of these iron-based solar cells or light-activated catalysts would increase considerably,” said Uhlig. “Through our discovery linked to these new iron-based solar cells, we hope to contribute important knowledge about how we are to meet the global energy challenge we are facing.”