Converting Absorbed Photons into Twice as Many Excitons: Successful High-efficiency Energy Conversion with Organic Monolayer on Gold Nanocluster Surface ―Applications Expected in Solar Energy Conversion, Material Conversion, and Medical Care―
September 24, 2019 Keio University
A research group comprising Associate Professor Taku Hasobe and Assistant Professor Hayato Sakai of Faculty of Science and Technology in the Keio University, Toshiyuki Saegusa of Graduate School of Science and Technology in the Keio University (completed master's program in 2019), and Professor Yasuhiro Kobori and postdoctoral researcher Hiroki Nagashima of Molecular Photoscience Research Center in the Kobe University found that when light was exposed to the surface of a tetracene alkanethiol-modified gold nanocluster, which they developed themselves, twice as many excitons could be converted compared to the number of photons absorbed by the tetracene molecules. They also found that these excitons have a lifetime that is approximately 10,000 times longer than that of the organic molecules on conventional gold surfaces. Furthermore, they succeeded in converting singlet oxygen (a type of reactive oxygen species) at a highly efficient conversion rate of 160%, far exceeding 100% conversion, in comparison to the number of absorbed photons. Singlet oxygen is used in photodynamic therapy (treatment of cancer with light) and organic synthesis, among other applications.
These findings are expected to contribute to areas such as solar energy conversion, electronics, life sciences, and medical care in the future. The outcomes of this research were published in the online version of the American scientific publication the "Journal of the American Chemical Society" on September 6.
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