Preparation and soft lithographic printing of nano-sized ITO-dispersions for the manufacture of electrodes for TFTs

The production of printed electronics exhibits an enormous economical potential due to the possibility to manufacture innovative products at low cost. At the moment, one of the major challenges for the fabrication of printed electronics is the controllability of the material properties during processing and the miniaturization of the deposited structures. In this context, the application of soft lithographic techniques appears promising, because they allow a defined patterning of the materials in the range of few nanometers, which is far below the limits of other printing techniques like inkjet-printing or screen printing. This work proves the applicability of the soft lithographic technique micro-molding in capillaries (MIMIC) for the manufacture of conductive indium tin oxide (ITO) electrodes. For the creation of stable dispersions of ITO nano-sized particles, steric as well as electrostatic stabilization concepts are applied. The prepared dispersions are characterized with regard to the later processing via MIMIC. The geometry and the electrical properties of the soft lithographically deposited structures are determined to prove their functionality. Special attention is paid to the influence of the wetting behavior of the dispersions on the resulting geometry of the structures. Finally, the applicability of the optimized structures is demonstrated by the assembly of a thin film transistor (TFT), in which the deposited structures serve as source and drain electrodes.