Poly(3-hexylthiophene), P3HT, has been widely used in organic electronics as a semiconductor material. It suffers from the low carrier mobility characteristics. This limits P3HT to be employed in applications. Therefore, the blending semiconductor material, carbon nanoparticle (CNP), and P3HT, are developed and examined by inkjet-printing organic field-effect transistor technology in this work. The effective carrier mobility of fabricated OFETs can be enhanced by 8 folds with adding CNP and using O2 plasma treatment. At the same time, the transconductance of fabricated OFETs is also raised by 5 folds. Based on the observations of SEM, XRD, and FTIR, these improvements are contributed to the local field induced by the formation of CNP/P3HT complexes. This observation presents an insight of the development in organic semiconductor materials. Moreover, this work also offers a low-cost and effective semiconductor material for inkjet-printing technology in the development of organic electronics. 1. Introduction Organic electronics have received tremendous interests due to their potential applications in flexible electronics. Moreover, characteristics of organic electronics including low-cost and low-temperature process also promote the value of this research field. Therefore, various organic electronic devices have been proposed and implemented, such as organic thin film transistors (OTFTs) [1], large-area displays [2], solar cells [3–5], organic light-emitting diodes (OLEDs) [6, 7], radio frequency identification tags (RFIDs) [8], and sensors [9]. Among various fabrication methods to implement these organic electronics, printing technology is emphasized because of its compatibility to large-area fabrications and industrial mass productions. The printing techniques can be achieved by spin coating, roll-to-roll printing, screen printing, gravure printing, and inkjet printing. In these established printing techniques, inkjet-printing is one of the most intriguing techniques. Without any prepatterned process, it can directly deposit ink materials following a designed pattern on substrates in an in-situ manner [10]. Compared with other solution-based printing processes, inkjet printing can reduce the ink material consumption by drop-on-demand design. It also overcomes the traditional contact and pattern-transferring problems. In addition, the high-resolution inkjet-printing techniques have been demonstrated up to 1？μm or less [11, 12]. As a consequence, organic materials with nanowires, nanoparticles, and nanocrystal-polymer composites have been successfully
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