| 초록 |
Recently, we had reported polyimide hybrid gate insulators with well-defined surface properties prepared by a hybridization with a specially designed polyimide with a long alkyl side chain and a poly(amic acid), which showed that an existence of the long alkyl chain of the polyimide at surface of the insulator gave a positive effect on the initial growth of the pentacene leading to the improvement of device performance. But, there were some problems like a high curing temperature and relatively low dielectric constant of of the poly(amic acid). Therefore, new polymeric insulators with bi-layered structure were prepared from polymers with relatively high dielectric constant as a bottom layer, which was coated with the polyimide with hydrophobic alkyl side chain. In this study, poly(vinylphenol) and poly(vinylidenedifluoride) were introduced as polymeric layers with high dielectric constant. The hydrophobic surface derived from the polyimide upper layer strongly affected an initial growth mechanism of the pentacene and subsequently the performance of the OTFTs. The performance of pentacene organic thin film transistors (OTFTs) with the bi-layered structure was superior to those of the OTFTs without the polyimide layer, which exhibited a carrier mobility of 0.20~0.41 cm2/V•s, on/off current ratio of around 8~9x10-4, a subthreshold slope of 1.8~2.4 V/dec and a current at off state of 2~7x~10-11 A. |
