TOP > News > The 44rd International Biomedical Engineering Seminar(November 10, 2026)
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| Date | November 10, 2026 14:00-15:30 |
| Venue | Meeting Room 1, 2nd Floor, University Hall, Yokohama Campus, Institute of Science Tokyo |
| Guest Speaker | Dr. Deepak Venkateshvaran(Cavendish Laboratory, University of Cambridge, U.K.) |
| Title | Unravelling the link between molecular mechanics and charge transport in organic semiconductors |
| Abstract | For decades, organic semiconductors have been prized for their mechanical flexibility. This raises a basic question: does softness limit how well they transport charge? My talk treats mechanics not as a property separate from transport but as inseparable from it. Afterall, macroscopic stiffness is the long-wavelength, zero-frequency limit of the acoustic phonon response, and the low-energy phonons it reflects are precisely those implicated in charge transport. To probe the link, I will show how atomic force microscopy serves as a real-space probe of molecular order and nanomechanics, complementing the reciprocal-space view from X-ray scattering. Higher-eigenmode imaging resolves polymer packing below one nanometre under ambient conditions, while force–distance spectroscopy maps local stiffness across the same surfaces [1]. In semicrystalline polymers, nanoscale stiffness tracks structural order [2], but more tellingly, the interconnectedness of stiff domains along the charge-transport direction is what tracks carrier mobility. In the molecular semiconductor series based on alkylated DNTT, side chains expand the unit cell to soften the crystal out-of-plane, yet stiffen it in-plane, in step with mobility [3]. Taken together, these results point to a common structural origin for mechanics and charge transport in molecular materials. They establish nanomechanical measurement as a tactile complement to scattering – reading structure in real space, where it matters most for transport – and provide new design guidelines for next generation molecular semiconductors with even higher mobilities than those today. |
Assoc. Prof. Hiroaki Iino(Sensing and Processing Research Core)
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