Hiroshi Kiguchi

Low-temperature polysilicon thin-film transistor driving with integrated driver for high-resolution light emitting polymer display

A high-resolution low-temperature polysilicon thin-film transistor driven light emitting polymer display (LT p-Si TFT LEPD) with integrated drivers has been developed. We adopted conductance control of the TFT and optimized design and voltage in order to achieve good gray scale and simple pixel circuit. A p-channel TFT is used in order to guarantee reliability in dc bias. An inter-layer reduces parasitic capacitance of bus lines. Because of the combination of the LT p-Si TFT and LEP, the display is thin, compact, and lightweight, as well as having low power consumption, wide viewing angle, and fast response.

26.3: Multicolor Pixel Patterning of Light-Emitting Polymers by Ink-Jet Printing

In order to realize a multicolor display, we tried to pattern three different colors to make pixels by using ink-jet technology. Light emitting polymer, poly(p-phenylene vinylene) (PPV), was successfully formulated into inks for ink-jet printing. Those inks showed a good ink-jetting behavior and became a good light emitting film. By combining the ink-jet printing with the self-patterning ability of the substrate, in which the hydrophilic and hydrophobic region is alternately constructed, an ink droplet can be patterned into the narrow pixel gap of 10 μm with precision of 1 μm order. We developed stacked structures combining PPV with Polyfluorene. It was confirmed that energy conversion from the wider gap layer to the smaller one occurred. As a result, we demonstrated the three color electroluminescence from the small pixels. This is the first demonstration of the fine pixel patterning of the multicolor light emitting polymers by ink-jet technology.

48.1: LTPS TFTs with Metal Electrodes Formed by Inkjet Printing Technology

Metal electrodes for low-temperature polycrystalline-silicon (LTPS) p-channel thin-film-transistors (TFTs) have been fabricated employing an inkjet technique. This technique has the potential to reduce device fabrication costs and energy consumption during the device fabrication. We have developed a fine-patterning technique employing the inkjet technique that is capable of producing metal lines with several μm widths by carefully controlling micro-liquid behavior and surface wettability. TFTs employing the inkjet technique show good performance and reliability as same as conventional LTPS TFTs. These results show that the inkjet technique can be used to fabricate high-performance LTPS TFTs at low cost.