Researchers fromIndian Institute of Science Education and Research (IISER) Thiruvananthapuramand IIT Indore have developed a new artificial light-harvesting system that can efficiently capture light for power conversion by mimicking photosynthesis, the process by which plants absorb sunlight and produce sugars.
The results of the study have been published in Chemical Science, a journal published by the prestigious Royal Chemical Society. The paper has been co-authored by Sukhendu Mandal, Associate Professor, Department of Chemistry, IISER Thiruvananthapuram, along with his research scholars Sourav Biswas and Anish Kumar Das; and Biswarup Pathak, Department of Chemistry, IIT Indore; along with research scholar Surya Sekhar Manna.
The researchers said scientists all over were focused on replicating the light-harvesting step of photosynthesis in engineered systems for use in solar cells or artificial leaves. The light-harvesting cores in plants and other photosynthetic bacteria are chromophores, which are molecules that absorb visible light and pass it on to other components that use the energy for various chemical reactions. The top-most chromophores that are exposed to the sun absorb the energy. The chromophores are arranged in arrays and and energised chromophore passes the energy to the adjoining chromophore, and so on. There is a rapid cascade of energy until the energy reaches its destination.
According to the authors, there have been many attempts at replicating the molecular and atomic structure of the light-harvesting mechanism in the laboratory. Polymeric structures, detergent-type molecules, vesicles, gels, and other bio-inspired structures, have been used to mimic photosynthesis. The most common problem faced by such molecules is that the light is quenched due to aggregation or bunching up of the molecules together. This leads to poor light capture and conversion efficiencies.
The scientists of IISER Thiruvananthapuram and IIT Indore have found a way to overcome the quenching problems of artificial light absorbers and transmitters. They have worked with clusters of silver that are of nanometer dimensions—a hundred thousand times smaller than the width of human hair. Such nanoclusters have fascinating structures and exotic photophysical properties. The researchers stabilised these nanoclusters with bulky ligands and entrapped the entire ensemble inside another large molecule called cyclodextrin.
They believe that this fundamental investigation into highly efficient energy transfer systems will provide the basis for designing new light-harvesting materials that can enhance the efficiency of solar cells and reduce energy loss. This is important given that India aims to achieve net zero carbon emissions by 2070 and to meet 50% of its electricity needs from renewable sources such as solar power by 2030.
