Capturing solar energy and converting it to electricity

The team has gone a step further, getting the system to produce electricity by connecting it to a thermoelectric generator. The hope is for this technology to lead to self-charging electronic gadgets that use stored solar energy on demand.

Kasper Moth-Poulsen, Research Leader and Professor at the Department of Chemistry and Chemical Engineering at Chalmers said: “This is a radically new way of generating electricity from solar energy. It means that we can use solar energy to produce electricity regardless of weather, time of day, season, or geographical location. It is a closed system that can operate without causing carbon dioxide emissions.”

The system is based on a specifically designed molecule of carbon, hydrogen and nitrogen. When this molecule is hit by sunlight it changes shape into an energy-rich isomer, a molecule made up of the same atoms but arranged together in a different way. The isomer can then be stored in liquid for up to 18 years for later use, for example at night or in winter. A specifically designed catalyst releases the saved energy as heat whilst returning the molecule to its original shape, so it can be reused in the heating system. The energy system can now, using a micrometre-thin thermoelectric generator, the energy system can also generate electricity to order.

A study published in Cell Reports Physical Science in March 2022, carried out in collaboration with Shanghai based researchers, takes the system a step further. The study retails how it can be combined with a compact thermoelectric generator to convert solar energy into electricity. The Swedish researchers sent the molecule, loaded with solar energy, to colleagues at Shanghai Jiao Tong University. The energy was released and converted into electricity using the generator developed in Shanghai.

“The generator is an ultra-thin chip that could be integrated into electronics such as headphones, smartwatches, and telephones. So far, we have only generated small amounts of electricity, but the new results show that the concept really works. It looks very promising,” said researcher Zhihang Wang from Chalmers University of Technology.

The research has potential for renewable, emission-free energy production. However, there is still a need for further research and development before anyone will be able to charge their technical gadget or heat their home with the systems stored solar energy.

“Together with the various research groups included in the project, we are now working to streamline the system. The amount of electricity or heat it can extract needs to be increased. Even if the energy system is based on simple basic materials, it needs to be adapted to be sufficiently cost-effective to produce, and thus possible to launch more broadly,” concluded Kasper Moth-Poulsen.