고분자 절연체내 불소가 ambipolar OFET의 전기적 특성에 미치는 효과에 관한 연구

Abstract

The Organic Field-Effect Transistors(OFETs) usually comprise electronic materials of wide conductivity covered from conductor to insulator and semiconductor. Although the OFETs represent field-effect transistors using “organic semiconductors” as an active layer, the performance of OFETs depends not only on the properties of the organic semiconductors, but is also affected by the properties of the gate dielectrics which contact directly with the active layer. Therefore, controlling the interface between the organic semiconductor and the gate dielectrics and the surface of the dielectric forming the interface is critical to optimize the OFETs. In this thesis, the top contact bottom gate (TCBG) structural OFETs consisting of an ambipolar semiconductor as an active layer and a newly-synthesized methyl-methacrylate-based triblock-copolymer as a gate dielectric was studied. In particular, the triblock-copolymer gate dielectrics, where benzene-contacting block in the triblock have no fluorine(F), and five Fs, respectively, were prepared to investigate the effect of the amount of F in the gate dielectric layer on the charge transports through the semiconducting film. The material without F was named ‘H’ and the material with five Fs in benzene was named ‘5F’. From our experimental results, it was revealed that the more F atoms in the gate dielectric enhanced the hole-transporting characteristics in the semiconducting copolymer. These results should be attributed to the difference in surface energy depending on the presence or absence of F of the two materials and the hole induction which is facilitated by the negative charge property of F.