Active-Matrix Backplane with Inkjet Printed Organic Thin-Film Transistors (OTFTs) for QR-LPD

Active matrix organic-TFT(OTFT) array for Quick-Response Liquid Powder Display (QR-LPD) was fabricated by use of inkjet printing technology. To define the shape and size of patterns formed by inkjet printing, we adopted a novel surface modification technique called photocatalytic lithography. Photocatalyst such as TiO2 oxidizes various organic materials in an excited state. Therefore photo-mask with a photocatalytic layer, irradiated with ultraviolet (UV) light, can oxidize selectively the surface of the organic material layer facing the phtocatalytic and then form hydrophobic and hydrophilic patterns. Ink-droplets ejected from ink jet print head spread only on the hydrophilic area and set like the mask pattern. We have developed to apply this technique to fabricating flat panel display components such as color filter, biomedical tools and so on. The combination of inkjet printing and photocatalytic lithography enables fine patterns to be formed in a few steps and at low cost. In this study, we obtained well-defined source and drain electrode in which the channel length is below 10 micron by use of inkjet and photocatalytic lithography. As a result, high contrast image consist of 10 inch, 80 dpi QR-LPD active matrix array was refreshed successfully.