POS5-1096
Asymmetrically Crosslinked Janus π-Ion Films as Reusable, Stackable Building Blocks for Reconfigurable Organic Electrochemical Transistors
When and Where
Nov 30, -0001
00:00 - 00:00
Presenter(s)
YongHee Kim (Pukyong National University)
Co-Author(s)
Abstract
Organic mixed ionic-electronic conductors (OMIECs) underpin much of modern bioelectronics, but free-standing π-ion films, composites combining a conjugated polymer with an ionic liquid (IL), remain mechanically weak, since the IL softens the polymer matrix and makes repeated peeling and reattaching difficult. While crosslinking the entire film bulk can improve rigidity, the film also compacts the amorphous regions responsible for ion transport, creating an inherent trade-off between mechanical robustness and ionic conductivity. This study overcomes that limitation by selectively crosslinking only one surface of the film. By applying UV light whose intensity decays with depth to a 4BX-doped poly(3-hexylthiophene) (P3HT):IL film, an asymmetric Janus architecture is produced in a single processing step, yielding a chemically strengthened top surface and a compliant, ion-abundant bottom surface. The crosslinked surface effectively restricts solvent-induced swelling and reduces the thermal expansion coefficient by roughly tenfold, without disturbing the π-π stacking of P3HT chains and hence without degrading charge-transport properties. The newly formed C-N-C bonds function as localized dipole sites that draw in ions, boosting interfacial capacitance by a factor of 3.5 and shrinking the hysteresis window of the resulting organic electrochemical transistor (OECT) from 3.26 V to 0.57 V. The mechanically reinforced film endures multiple cycles of detachment and reattachment and can be vertically laminated into multilayer OECTs, allowing device performance to be tuned post-fabrication simply by adjusting the number of stacked layers and their orientation. Demonstrations in flexible and skin-attached touch sensors confirm that the Janus π-ion film serves as a versatile, modular component for next-generation reconfigurable organic bioelectronic systems.
