[19a-E302-1~10] 12.2 Characterization and Materials Physics

△ [19a-E302-3] The interfacial dynamics of ionic liquid causing operational instability of electric double layer organic FET

〇Daijiro Okaue¹, Sakurako Ono¹, Kota Sakamoto¹, Hiroaki Nato¹, Taiki Sato¹, Ichiro Tanabe¹, Akihito Imanishi¹, Jun Takeya², Ken-ichi Fukui¹ (1.Osaka Univ., 2.Univ. Tokyo)

Keywords:Electric double layer organic FET, Ionic liquid, Carrier trap

The purpose of this research is to elucidate the origin of the instability of an ionic liquid (IL) gated electric double layer organic FET. We focus on the unique interfacial dynamics of IL on the molecular scale under device operation condition. Operando electrochemical impedance spectroscopy revealed that the carriers were trapped in the organic semiconductor and, they caused “bias stress”. We focused on the first interfacial IL behavior experimentally and theoretically on the molecular scale by FM-AFM measurement and MD simulation, respectively. As a result, interfacial IL structure changed from random to a very uniform layer at the on-state of the device. This uniform layer structure may effectively trap the carriers. By energetic analyses from the temperature dependent device performance measurement, carrier trapping process can be explained with the equilibrium between two types of interfacial IL structure, that is, the random (OFF state) and the uniform structure (ON state).