Diagram of an exciton within a tetracene crystal, used in these experiments, shows the line across which data was collected. That data, plotted below as a function of both position (horizontal axis) and time (vertical axis) provides the most detailed information ever obtained on how excitons move through the material.Illustration courtesy of the researchers A quasiparticle called an exciton — responsible for the transfer of energy within devices such as solar cells, LEDs, and semiconductor circuits — has been understood theoretically for decades. But exciton movement within materials has never been directly observed. Now scientists at MIT and the City College of New York have achieved that feat, imaging excitons’ motions directly. This could enable research leading to significant advances in electronics, they say, as well as a better understanding of natural energy-transfer processes, such as photosynthesis. The research is described this week in the journal Nature Communications, in a paper co-authored by MIT postdocs Gleb Akselrod and Parag Deotare, professors Vladimir Bulovic and Marc Baldo, and four others. “This is the first direct observation of exciton diffusion processes,” Bulovic says, “showing that crystal structure can dramatically affect the diffusion process.” “Excitons are at the heart of devices that
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