Associate Professor, Ulsan National Institute of Science and Technology (UNIST), Republic of Korea

Biography: Jang-Ung Park achieved his Ph.D. from University of Illinois at Urbana-Champaign (UIUC) in 2009. After that, he went on to work as Postdoctoral Fellow at Harvard University. He is now an Associate Professor in School of Materials Science and Engineering at UNIST. His current research is focused on nanomaterials synthesis and wearable electronics.

Speech Title: Fabrication of Stretchable, Transparent Electronic Devices Using Cellulose Composites
Abstract: Efforts to develop alternative substrate materials beyond conventional plastic substrates have grown rapidly in recent years for demanding applications in flexible and wearable electronics. Abundant, bio-degradable, and sustainable cellulose nanofiber based substrates have attracted much interest as a promising alternative for flexible electronics due to their outstanding properties, such as high mechanical strength, optical transparency, and exceptionally low coefficient of thermal expansion. Here, we report an unconventional approach to realize a high performance CNF-epoxy composite substrate by simultaneous electrospinning and spraying process. The resulting CNF-epoxy composite substrate shows high transmittance (88% at 550 nm) and superb mechanical robustness (Young’s modulus and tensile strength of 4.3 GPa and 160 MPa, respectively), as well as outstanding thermal stability (coefficient of thermal expansion as low as 10 ppm/K). A flexible touch-screen panel and a highly transparent organic light-emitting diode are demonstrated as potential applications adopting the CNF-epoxy composite substrate. We also introduce a substrate in a foldable and stretchable form exploiting the photo-patternability of the composite which can be utilized for origami electronics. The versatility of the cellulose nanofiber-epoxy composite substrate, together with its outstanding mechanical, optical, and thermal properties, provides a fertile ground for the realization of next-generation flexible and wearable electronics.