Sheets are highly efficient solar cells that can convert up to 40% of the received light into chemical energy, which is much more efficient than conventional silicon-based solar cells which have an efficiency of around 15%.
In the first phase of photosynthesis, sunlight is absorbed and converted into stored chemical energy in the form of adenosine triphosphate (ATP) molecules. These reactions take place at the level of chlorophyll molecules which are located in the membranes of thylakoids, inside the chloroplasts of plant cells.
Researchers at the University of Sydney in Australia have synthesized chlorophyll-type molecules that are capable of converting light into electrical energy, that is, of reproducing the first phase of photosynthesis. The molecular structure of natural chlorophyll consists of a nitrogenous porphyrin ring with a magnesium ion in its center. Synthetic replicas have more than a hundred porphyrins grouped around a tree molecule to mimic the structure of natural photosynthetic systems.
Tests have shown that the conversion of light into electrical energy is more efficient when the synthetic molecules are not too large. The best results are obtained with molecules the size of which is approximately half the wavelength of the light absorbed, that is to say between 300 and 800 nanometers in the case of visible light.
The integration of such structures in photovoltaic solar cells will improve their efficiency. The team is now working to make prototypes of cells incorporating the synthetic molecules before embarking on commercial production of solar panels in collaboration with Osaka University in Japan.