Abstract
Organic thin-film transistors have been attracting much interest as backplane of displays. Especially, it is possible to fabricate low cost, flexible, and large area backplane for display when soluble organic semiconductors are used for active layer as we can make TFTs by printing methods. In addition,it needs to be printed not only organic semiconductor, but also electrodes, insulators, and any other components of TFTs, and also needs to be developed printing technologies for them.
We have been developed an "offset-based printing technology". It is possible to fabricate a high resolution pattern such as 1 m with thin film (100 nm). We also have been brushed up a conventional relief printing for organic semiconductor layer with optimization of printing process components and conditions. We found that when we use this printing process for organic semiconductor layer, it is possible to get a very high uniformity of transistor characteristics.
In this paper, we developed an all-printed 150 ppi flexible organic TFT array and it could successfully drive 5.35 inch E Ink electrophoretic electronic paper. A poly-ethylene-naphthalate (PEN) film was used for the substrate and all the components were printed without any photo-assist process or any photo-lithographical process. The printed OTFTs showed over 0.2 cm2/Vs mobility and excellent uniformity.
