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Proceedings Paper

Printable organic TFT technologies for FPD applications
Author(s): Masahiro Kawasaki; Masahiko Ando; Shuji Imazeki; Yoshifumi Sekiguchi; Shoichi Hirota; Hiroshi Sasaki; Sei Uemura; Toshihide Kamata
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Paper Abstract

In this paper, we introduce our recent results on organic thin-film transistor (TFT) technologies; self-aligned self-assembly process and a high-resolution color active-matrix LCD panel driven by organic TFT. First, a novel process for fabricating alignment-free, printable, organic thin-film transistors is presented. This process exploits a self-assembly phenomenon in which soluble nanomaterials such as metal nanoparticles and organic molecules are self-assembled into a device structure. Solution-processed source and drain electrodes were self-aligned to a gate electrode by using a hydrophobic self-assembled monolayer optically patterned onto the gate electrode with a back-substrate exposure technique. An organic semiconductor film deposited on the patterned SAM was selectively ordered and substantially self-aligned to the gate electrode. A field-effect mobility of 0.15 cm2/Vs and on/off current ratio of 105 were experimentally demonstrated when pentacene molecules were used as the semiconductor and silver nanoparticles were used as electrode materials. Second, a full-color twisted-nematic type liquid crystal display (TN-LCD) of 1.4-inch diagonal size driven by organic TFT has been fabricated. This TN-LCD has 80 x 80 x 3 (RGB) pixel arrays addressed by pentacene TFT with a channel width of 50 μm. The contact resistance between the pentacene film and the source/drain electrodes has been reduced by steepening the side slope of the electrodes. In addition, a solution-processed passivation film with a novel structure, consisting of organic and inorganic stacked layers, has been developed to protect the TFT against degradation induced by integration with TN-LCD devices. Consequently, the organic-TFT-driven TN-LCD is capable of displaying full-color moving images at a resolution of 80 pixels per inch.

Paper Details

Date Published: 22 September 2005
PDF: 10 pages
Proc. SPIE 5940, Organic Field-Effect Transistors IV, 59400Q (22 September 2005); doi: 10.1117/12.614835
Show Author Affiliations
Masahiro Kawasaki, Hitachi, Ltd. (Japan)
OITDA (Japan)
Masahiko Ando, Hitachi, Ltd. (Japan)
OITDA (Japan)
Shuji Imazeki, Hitachi, Ltd. (Japan)
OITDA (Japan)
Yoshifumi Sekiguchi, Hitachi, Ltd. (Japan)
Shoichi Hirota, Hitachi, Ltd. (Japan)
Hiroshi Sasaki, Hitachi, Ltd. (Japan)
Sei Uemura, National Institute of Advanced Industrial Science and Technology (Japan)
Toshihide Kamata, National Institute of Advanced Industrial Science and Technology (Japan)

Published in SPIE Proceedings Vol. 5940:
Organic Field-Effect Transistors IV
Zhenan Bao; David J. Gundlach, Editor(s)

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