During photosynthesis, plants use sunlight to convert carbon dioxide and water into sugars and oxygen. Scientists seek to mimic this sequence of highly complex reactions to develop new processes to synthesize biofuels using solar energy. "One of the most interesting elements of photosynthesis is the photosynthetic antenna," says Bruno Robert, a researcher at the Frédéric-Joliot Institute. "It is a molecular device for harvesting sunlight, which triggers the swift transfer of electrons from water to carbon dioxide. Yet, to function properly, these photosynthetic antennas need the protection provided by chemical pigments called carotenoids."

In collaboration with four other teams from Yale University, Arizona State University, Argonne National Laboratory, and the Institute of High Performance Computing in Singapore, researchers from the Frédéric-Joliot Institute have identified how these pigments responsible for protecting photosynthetic antennas operate. "Just like paintings whose colors fade when exposed to sunlight, the materials for photo-conversion suffer from a process of degradation," Robert said. "Nature has developed systems that use carotenoids to absorb excess energy and protect photosynthetic antennas from decomposition. In our study, we have revealed the parameters and the mechanisms governing a fundamental process for photoprotection: the transfer of energy to molecules that are capable of quickly trapping undesired energy." In plants, these transfers are 1,000 times faster than in anaerobic organisms. By taking into account the structure of the molecules involved, as well as the presence of amino acids around these molecules, the scientists modeled differences in kinetics. As a result, they got a detailed understanding of the parameters underlying the efficiency of these transfers. In particular, they showed that a specific configuration of carotenoids allows for an improved transfer from the chlorophyll molecules.

Understanding this process and characterizing "digital footprints" to identify the specific pigments involved are two essential requirements to design solar energy systems protected by annex molecules, which, as a result, would become more stable over time.