October 1, 2024
Tokyo University of Science
Keio University
A research group led by Professor Takanori Fukushima and Assistant Professor Tomoya Fukui of the Institute of Chemical and Life Science, Research Centers and Institutes for Interdisciplinary Science / Autonomous Systems Materials Research Center (ASMat) at Tokyo University of Science*, graduate student Masato Fukumitsu of the Department of Applied Chemistry, School of Materials and Chemical Technology at the same university, and Professor Taku Hasobe of the Department of Chemistry, Faculty of Science and Technology at Keio University, has developed an organic thin film in which pentacene units are two-dimensionally integrated. Using an approach that employs a supramolecular scaffold to assemble various molecular units and polymers into a two-dimensional structure, the group discovered that in this assembled structure, pentacene exhibits both rapid singlet fission and subsequent high-efficiency free triplet generation.
Singlet fission is a phenomenon in which two excited triplet states are generated from a single excited singlet state. Because it can, in principle, form two excitons from a single photon, it has attracted significant attention for improving the performance of thin-film solar cells and optoelectronic devices. To achieve efficient singlet fission in the solid state, a spatial design is required that ensures chromophores are in close proximity to each other while also securing space around them to accommodate the conformational changes of the chromophores that occur during the singlet fission process. However, a rational methodology for realizing such an assembled structure had not been established.
In this study, the researchers succeeded in two-dimensionally integrating pentacene into an arrangement that simultaneously satisfies the two conditions required for efficient singlet fission: "proximity" of the chromophores and "securing space" around them. This was achieved using an approach that employs a tripod-shaped triptycene supramolecular scaffold. This approach enables the design of binary molecular assemblies that can elicit the optoelectronic functions of chromophores and is expected to have applications in the development of next-generation energy devices.
This research was published as an open-access article in the journal " Science Advances " on September 13 (US Eastern Time).
*On October 1, 2024, Tokyo Medical and Dental University and Tokyo Institute of Technology merged to form Tokyo University of Science (Science Tokyo).
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