Gold medal to chemistry students for solar cell theory – University of Copenhagen

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02 December 2014

Gold medal to chemistry students for solar cell theory

Gold medal

Putting the brakes on climate change requires optimizing the capture, storage and use of solar energy. However, today’s solar cells suffer from a few weaknesses: They can capture solar energy but are unable to store it. The cells are made of silicon, which is rigid and fragile, and because they contain heavy metals, they pose an environmental hazard. Chemistry PhD student Stine Tetzschner Olsen wants to change all that. This is what has piqued her interest in what are known as ‘dihydroazulene photoswitches and stimulated the work on her gold medal winning paper, “Quantum-mechanical insights in molecular electronics in the Coulomb blockade regimen – molecular transistors, sensors and contacts.”

Promising molecular solar battery

Dihydroazulene is a molecule with very promising properties for solar battery use. It can capture solar energy, store it and release it as heat, as well as do something entirely new and quite critical. When the heat is to be released, the molecule can be stimulated by electricity. Previously, it was impossible to have direct control of when the molecule released energy in the form of heat.

A solar battery that is unable to release energy/heat on demand isn’t a very practical one. So ‘switching’ the Dihydroazulene with electrical current was a necessary advancement. However, developers at the Department of Chemistry’s ‘Centre for Exploitation of Solar Energy’, headed by Professor Mogens Brøndsted, had a problem. They didn’t understand why current functioned as a switch. Stine Tetzschner Olsen explains:

“Mogens was the first to get the photoswitch to switch without the help of light. This lead to what is known as the “dark photoswitch”, which is a bit of a paradox. Just consider the contrasting terms – dark and photo, with photo referring to light,” says Olsen.

Fundamental understanding a prerequisite for application

Tetzschner Olsen’s research has opened new doors for understanding potential “solar heat batteries”. The method can be used in the development of other photoswitches to find out if there are any other candidates that can be switched on in the dark with a bit of voltage.

“The first step in developing this potential solar heat battery is to understand the molecule being used,” states Olsen.

Gold for pure computational chemistry

The gold medal winning paper is titled “Theoretical Investigations on Dihydroazulene Photo-switch in the Coulomb Blockade Regime - Future Aspects on Solar Cells”, and its author points out it is pure computational chemistry. “I had worked with computational methods before, but the interpretation of my theoretical figures vis-à-vis real experimental observations was incredibly exciting and challenging,” says the PhD student.

Recognition and advertizement

The dissertation supervisor is Kurt V. Mikkelsen, but Olsen’s previous thesis co-supervisor, Thorsten Hansen, was also involved with the project. Stine Olsen sees the medal as of benefit to her both now and in the future.

“It is always terrific to gain recognition for one’s work, and to know that you are good enough,” smiles Olsen and continues: “And, it looks good on the resumé, so hopefully that will help when I go out into the real world looking for a job,” concludes the gold medal winning PhD chemist.