무용매 공정과 직접 패턴이 가능한 실세스퀴옥산 탑 게이트 유기 트랜지스터용 게이트 유전체 (Solvent-Free Processable and Directly Photo-Patternable Silsesquioxane Gate Dielectrics for Top-Gate Organic Transistors)

Top-gate organic field-effect transistors (OFET) have a problem that, when the gate dielectric layer is formed by solution processes, the underlying organic semiconductor layer is damaged. To solve this problem, we have developed organic–inorganic hybrid gate dielectric materials that can be prepared by a solvent-free method. To apply the solvent-free process, the dielectric material must be in a liquid state and can be later converted to solid to provide sufficient dimensional stability. Thus, we synthesized a liquid-phase poly(mercaptopropyl- co-vinyl)silsesquioxane (PMPVSSQ) that could be cross-linked by UV irradiation.
The synthesized polymer was spin-coated on a silicon wafer after mixing with a photoinitiator and then cured through the thiol-ene reaction by UV irradiation to form a highly crosslinked film. In addition, a negative tone pattern was successfully formed by the conventional photolithography process. The leakage current of the dielectric film was lower than that of the conventional polymer gate dielectric due to the highly crosslinked structure. A top-gate OFET was fabricated using poly(3-hexylthiophene), a p-type organic semiconductor, and the transfer characteristics of the fabricated device showed excellent stable operation as a typical transistor. This showed that the dielectric forming process did not affect the semiconductor layer because no solvent was used.

Top-gate organic field-effect transistors (OFET) have a problem that, when the gate dielectric layer is formed by solution processes, the underlying organic semiconductor layer is damaged. To solve this problem, we have developed organic–inorganic hybrid gate dielectric materials that can be prepared by a solvent-free method. To apply the solvent-free process, the dielectric material must be in a liquid state and can be later converted to solid to provide sufficient dimensional stability. Thus, we synthesized a liquid-phase poly(mercaptopropyl- co-vinyl)silsesquioxane (PMPVSSQ) that could be cross-linked by UV irradiation.
The synthesized polymer was spin-coated on a silicon wafer after mixing with a photoinitiator and then cured through the thiol-ene reaction by UV irradiation to form a highly crosslinked film. In addition, a negative tone pattern was successfully formed by the conventional photolithography process. The leakage current of the dielectric film was lower than that of the conventional polymer gate dielectric due to the highly crosslinked structure. A top-gate OFET was fabricated using poly(3-hexylthiophene), a p-type organic semiconductor, and the transfer characteristics of the fabricated device showed excellent stable operation as a typical transistor. This showed that the dielectric forming process did not affect the semiconductor layer because no solvent was used.