Plants and other photosynthetic organisms use a wide variety of pigments to absorb different wavelengths of light. MIT researchers have now developed a theoretical model to predict the spectrum of light absorbed by aggregates of these pigments, based on their structure. The new model could help guide scientists in designing new types of solar cells made of organic materials that efficiently capture light and funnel the light-induced excitation, according to the researchers. “Understanding the sensitive interplay between the self-assembled pigment superstructure and its electronic, optical, and transport properties is highly desirable for the synthesis of new materials and the design and operation of organic-based devices,” says Dr. Aurelia Chenu, an MIT postdoc and the lead author of the study, which appeared in Physical Review Letters on January 3, 2017. The article is titled “Construction of Multichromophoric Spectra from Monomer Data: Applications to Resonant Energy Transfer.” Photosynthesis, performed by all plants and algae, as well as some types of bacteria, allows organisms to harness energy from sunlight to build sugars and starches. Key to this process is the capture of single photons of light by photosynthetic pigments, and the subsequent transfer of the excitation to the reaction centers, the starting point of chemical conversion. Chlorophyll, which absorbs blue and red light, is the best-known example of photosynthetic pigments, but there are many more, such as carotenoids, which absorb blue and green light, as well as others specialized to capture the scarce light available deep in the ocean.
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