Key principle to boost efficiency of artificial photosynthesis and next-generation semiconductors
A research team led by Taeyeon Kim, a professor in the Department of Chemistry at Sungkyunkwan University, in collaboration with a team from Yonsei University, has identified a new principle that controls charge separation, a phenomenon that plays a central role in both plants' generation of electrical energy (photosynthesis) and next-generation molecular semiconductor devices.
Researchers at Sungkyunkwan University and Yonsei University have uncovered a key principle that could enhance the efficiency of artificial photosynthesis and next-generation semiconductors. This principle revolves around charge separation, a fundamental process in both photosynthesis and emerging molecular semiconductor devices.
By mimicking the rapid charge separation observed in plants, the researchers aimed to develop advanced energy devices. They focused on a type of organic semiconductor molecule called perylene bisimide (PBI), which has shown promise in these applications. However, the tightly packed arrangement of PBI molecules made it challenging to study how the surrounding environment influences charge transfer.
To overcome this challenge, the team devised a platform that allowed them to selectively alter the polarity of the solvent while maintaining the molecular structure. Using ultrafast laser spectroscopy, they observed that the mechanism of charge transfer changes depending on the solvent's properties. In low-polarity solvents like oil, charge transfer occurs through quantum-mechanical tunneling, while in high-polarity solvents like water or alcohol, it is driven by the collective movement of solvent molecules.
This "mechanism crossover" was a first of its kind discovery. Moreover, the researchers found that under intense light, the distance over which light energy can travel (exciton diffusion length) could be adjusted from 35.9 nanometers to 98.8 nanometers, depending on the solvent environment. This discovery not only sheds light on the fundamental principles governing charge transfer in complex molecular aggregates but also opens up new avenues for designing highly efficient organic semiconductors and artificial photosynthesis systems.
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