| AVS 55th International Symposium & Exhibition | |
| Nanomanufacturing Focus Topic | Thursday Sessions |
| Session NM+EM+PS+NS+NC-ThM |
| Session: | Printable Lithography and Processing |
| Presenter: | D.R. Hines, University of Maryland |
| Authors: | D.R. Hines, University of Maryland V.W. Ballarotto, Laboratory for Physical Sciences C. Hull, Laboratory for Physical Sciences G.S. Oehrlein, University of Maryland D.Y. Lee, University of Maryland C.M. Stafford, National Institute of Standards and Technology C.L. Soles, National Institute of Standards and Technology E.K. Lin, National Institute of Standards and Technology J. Liu, National Institute of Standards and Technology J.-Y. Chung, National Institute of Standards and Technology S.G. Walton, US Naval Research Laboratory E.H. Lock, US Naval Research Laboratory |
| Correspondent: | Click to Email |
High quality organic & carbon-based thin-film transistors (TFT) have been successfully fabricated onto plastic substrates using transfer printing. With this printing process, each device component (conducting electrodes, polymer dielectric layer and semiconductor layer) was printed using only pressure and temperature, eliminating all chemical processing on the plastic device substrates. Pentacene (Pn), poly(3-hexylthiophene) (P3HT), carbon nanotube mats (CNTM) and graphene TFTs were all fabricated on polyethylene terephthalate (PET) substrates. Bottom gate, bottom source/drain devices yielded mobilities of 0.237 cm2/Vs for Pn and 0.04 cm2/Vs for P3HT. Bottom-gate CNTM TFTs exhibited p-type behavior, mobilities of 13.7 cm2/Vs, on/off ratio of 103 and minimal hysteresis. Top-gate graphene TFTs exhibited mobilities of 1.0x104 cm2/Vs for holes and 4x103 cm2/Vs for electrons. The organic TFT devices were fabricated using a variety of polymer dielectric layers including poly(hydroxystyrene) (PHS), polystyrene (PS), polycarbonate (PC) and poly(methylmethacrylate) (PMMA). The resulting TFTs showed little variation in mobility, but strong variation in threshold voltage for different dielectric layers. The transfer printing process relies primarily on differential adhesion for the assembly of both patterned and unpatterned films onto a common flexible, plastic substrate. It is a simple and robust process that is compatible with a wide range of materials. Plasma processing techniques are being adapted to control the surface energy of polymer and plastic surfaces in order to increase adhesion forces at the interface between polymer dielectric layers and plastic substrates. The printability and surface characterization of plasma treated polymer/plastic surfaces will be discussed. One goal of this work is to enable the incorporation of many different dielectric materials (including 10 test polymer dielectric films) and substrate materials (including 11 test plastic substrate sheets) into the fabrication of flexible electronics. This work partially supported by the Office of Naval Research and the Laboratory for Physical Sciences. *E.H. Lock, NRC/NRL Postdoctoral Research Associate.