Energy Revolution Is the Energy-Storing Solar Cell Coming?

Energiespeichernde Solarzellen könnten zum Gelingen der Energiewende beitragen.

Storing solar energy is a central challenge of the energy transition. One research approach is the conversion and storage of solar energy in a single molecule.

Electricity from renewable energy sources such as the sun or wind is only available when the wind blows and the sun shines. If little electricity is needed at this time, it is very difficult to store the remaining electricity. Scientists at the Friedrich Alexander University Erlangen-Nuremberg are working on new solutions and are focusing on chemical concepts for energy storage.

In two joint projects, the scientists are looking for new ideas for the molecular storage of solar energy. They are investigating molecules and processes that enable both efficient storage and controlled energy release. It is even conceivable that the stored chemical energy could be directly converted into electrical energy. This would enable the construction of an energy-storing solar cell.

Storing Solar Energy

The research is based on the so-called »norbornadiene quadricyclane storage system«. The substances norbornadiene (NBD) and quadricyclane (QC) are hydrocarbons and havebeen discussed by experts as potential candidates for the storage of solar energy for a long time: Under the influence of light, the molecule norbornadiene can transform into quadricyclane in a reaction within the molecule. This achieves an energy density equivalent to that of a high-performance battery. Because of this property, quadricyclane is also referred to as »solar fuel«.

Efficient Storage

In the sub-project »Photochemically and magnetochemically triggered storage / release of solar energy in strained organic compounds«, led by Prof. Dr. Dirk Guldi and Prof. Dr. Andreas Hirsch, the scientists are working on the production of various new families of NBD and QC derivatives.

In addition, they systematically investigate the influence of photosensitizers and electron acceptors as well as solvents and magnetic fields within this process. The long-term goal of the researchers is to realize a closed system fuel cycle for molecular storage media.

Controlled Energy Release

In the sub-project »Catalytic and electrochemical reproduction of solar energy stored in strained organic compounds« Prof. Dr. Julien Bachmann, Prof. Dr. Jörg Libuda and Dr. Christian Papp are developing new catalyst systems and electrodes with which chemical energy can be converted directly into electrical energy. They want to prove this functional principle conceptually by means of hybrid interfaces with suitable electronic structure, chemical structure, and electrochemical stability.

The results of the two subprojects, for which funding of more than 1 million euros from the German Research Foundation is available, could form the basis for the construction of an »energy-storing solar cell«.