Organic thin film transistor (OTFT)-based electronics performing simple operations/functions offer unique attractions compared to traditional inorganics, including flexibility, light-weight, and inexpensive large-area coverage and integration. Many studies have focused on the development of high performance polymer semiconductor materials and methods for improving their ordering to achieve high charge carrier mobility via inter-molecular hopping. Equally important, however, is the availability of high-performance gate dielectrics.
A technologically relevant gate dielectric material should not only exhibit low charge trap density and negligible leakage currents (a prerequisite to enhance mobility and device performance for a given organic semiconductor), but must be solution-processable, compatible with both p- and n-channel semiconductors, and enable high device yields over large area. Although many efforts have been done to improve the properties of OTFTs, there are still some issues to be explored. Main challenge is controlling the properties of the organic dielectric, which is printed in large area for low voltage OTFTs.
In this thesis, a fluorinated styrene-alt-maleicanhydride copolymer (FSMA) gate dielectric, low surface energy and good wetting property on gate substrate, was synthesized and pentacene (p-type) and $C_{60}$ (n-type) OTFTs using FSMA as gate dielectric were fabricated. Although maleic anhydride, hydrophilic mobility, is used as comonomer for the preparation of FSMA, its surface tension is still hydrophobic compared with fluorinated organic SAM, i.e. FOTS. The leakage current of FSMA with metal-insulator-metal sandwich structure exhibited superior insulating properties vs. corresponding homopolymer. To fabricate low-voltage operating OTFTs, cross-linking of FSMA dielectric was employed by dipping spin-coated FSMA on gate substrate into alkyl diamine solution, which is well-known reaction between anhydride and amine in organic chemistry. The c...