To be a high performance device, the ink-jet printing of organic layer faces to the challenge of ring edge behavior which makes the uneven film and deteriorate device, due to the capillary force driving from center toward to edge. Another difficulty is the narrowing of channel width by ink-jet printing of organic layer meets the tough to be under micrometer scale. The limitation comes from state-of-the art of ink-jet printing because of its large drop size and jetting variation. In this study, a novel process by inkjet printing of dilute PMMA solution to form separation bank as confined boundary for the subsequent depositing PEDOT was proposed, where the PEDOT was as the source and drain electrode with gap of several micrometers due to the innate characteristic of ring edge of ink jetted PMMA. Using this technique, the organic device constructed with bottom gate and evaporation of Pentance shown satisfactory performance.
Jhih-Ping Lu, Hsuan-Ming Tsai, Ying-pin Chen, Yuh-Zheng Lee, Kevin Cheng, Fang-Chung Chen, "Ring Edge in Film Morphology: Benefit or Obstacle for Ink-Jet Fabrication of Organic TFTs" in Proc. IS&T Digital Fabrication Conf., 2006, pp 155 - 158, https://doi.org/10.2352/ISSN.2169-4451.2006.22.2.art00048_3