Scientists have discovered a way to boost the efficiency of light-harvesting systems using genetically engineered viruses.
The researchers achieved their feat through exotic effects of quantum mechanics referred to as "quantum weirdness," the Massachusetts Institute of Technology reported. The effects include a particle's fascinating ability to exist in more than one place in space and time.
Photosynthesis can produce quantum particles of energy, also known as excitons, that jump from one chromophore to another to reach a reaction center that allows them to harvest energy. The path the exciton takes across the chromosphores can be inefficient, so it must take multiple pathways at once and select the best ones. In order for this to be possible, the particles must be perfectly arranged in what is called the "Quantum Goldilocks Effect."
The researchers engineered a virus that could bond with multiple synthetic chromophores. They also produced a variety of virus sizes and spacings between the synthetic chromophores, and selected the ones with the best performance. This breakthrough proved to more than double excitons' speed and increase the distance they could travel before disappearing, greatly improving efficiency. Once the virus was engineered, the researchers used laser spectroscopy and dynamical modeling to watch the light-harvesting process in real-time.
"It was really fun," said MIT professor Angela Belcher, an expert on engineering viruses to carry out energy-related tasks. "A group of us who spoke different [scientific] languages worked closely together, to both make this class of organisms, and analyze the data. That's why I'm so excited by this."
The researchers noted the study results offer a proof of concept as opposed to an actual system, but could lead to the development of inexpensive and efficient solar cells. The viruses can harvest and transport energy from light, but cannot yet harness it to produce power or molecules like what is seen in photosynthesis. In the future the researchers hope to solve this problem by adding a reaction center where the process can be completed.
"Access to controllable excitonic systems is a goal shared by many researchers in the field," said Alán Aspuru-Guzik, a professor of chemistry and chemical biology at Harvard University who was not involved in the study. "This work provides fundamental understanding that can allow for the development of devices with an increased control of exciton flow."
The findings were published in a recent edition of the journal Nature Materials.