Undergraduate Researcher Helps Decode Solar Energy Capture
By Chloe de Leon
Plants turn sunlight into energy. It is one of the most well-known scientific concepts that we learn. But as straightforward as photosynthesis may seem, scientists have yet to explain the chemical and physical mechanisms that make plants so highly efficient at harvesting sunlight.
Undergraduate student Jacob Lydon’s research is helping to reveal how photosynthetic proteins in plants achieve near-perfect light-harvesting efficiency. With an interest in the intersection of chemistry and physics, Lydon began conducting research this semester in Assistant Professor Minjung Son’s (Chemistry, MSE) physical chemistry research group.
Son’s lab contains several sub-teams that explore the mechanisms of light harvesting in different components of the photosynthetic apparatus, like chlorophyll and carotenoids. Lydon and graduate student Rebecca Gracia study chlorophyll a. This molecule is the primary light-harvesting pigment found in most organisms that perform photosynthesis. Lydon and Gracia’s research focuses on photons captured by chlorophyll a’s intense absorption peak, known as the Soret band, which appears in the blue light region of the visible solar spectrum.
Lydon studies these molecules within a photonic platform known as exciton-polaritons. Exciton-polaritons are a mixed state between light and molecules that form when a photon couples with an electronic transition in a pair of mirrors. The light trapped in between the mirrors can strongly interact with the molecular transition, resulting in modification of the properties and energy flow pathways of the molecule. Lydon inserts chlorophyll molecules in a pair of silver mirrors to create exciton-polaritons and then uses laser spectroscopy to analyze how this light-matter coupling alters their photophysical properties.
“This allows us to see how light-matter interaction impacts the energy transfer timescales of chlorophyll,” said Lydon. “In general, [it] will help explain why energy transfer in the photon capture step of photosynthesis is so efficient.”
In the lab, Lydon aligns lasers, fabricates materials, and conducts spectroscopy. He processes the data from these experiments outside of the lab, analyzing exciton-polariton formation and relaxation timescales. Lydon and Gracia repeat this process under varying conditions to understand how different factors influence photosynthetic light harvesting. This research has provided Lydon with the opportunity to learn beyond the content of his undergraduate courses, including methods in spectroscopy and materials science.
Lydon is hopeful that insights from this research could one day inform clean energy technology such as solar panels, where improving photon capture is critical to boosting overall photovoltaic performance. Continuing his research into the next semester, Lydon expressed excitement for the work ahead of him.
“We have some good results, but there’s a lot more work to be done,” Lydon said.