Cationic effects on solid polymer electrolyte-gated organic transistors

Abstract

Unlike the conventional organic field effect transistors using traditional gate dielectric layer, the electrolyte-gated organic transistors (EGOTs) use electrolytes as gate media, resulting in a tunable highly conductive channel. Due to their unique advantages, such as: higher gate-capacitance and lower operating voltages, the EGOTs are subject to extensive research. In a solid polymer electrolyte gate, the solvated cations and anions are initially evenly distributed in the ion-conducting polymer, under gate bias, the counter ions then drift towards the electrolyte/active layer interface and under high enough bias they might insert into the active layer and dope the polymer. Given the above mechanism, the anions and cations play the crucial role for gate operation in EGOTs. Although how the anions significantly affect the organic electrochemical transistors using the liquid electrolyte media was investigated, the ionic effect in the solid electrolyte-gated transistors has been barely reported. In this work, the effects of cation on the device performance of solid polymer electrolyte-gated organic transistors have been systematically studied. In the devices made with alkali perchlorates, a systematic shift in threshold voltage, current hysteresis, and response time with increasing cation size/mass has been observed. A lower threshold voltage is obtained with the smaller cation which also displays smaller hysteresis and faster response due to faster migration of smaller cations in polymer electrolyte. This study suggests the smaller cations should be used in the fabrication of solid polymer EGOTs. • Cationic effects on the solid electrolyte (PEO:alkali perchlorate salt)-gated organic transistors (EGOTs) are studied. • The smaller cation based device displays lower threshold voltage, smaller hysteresis, and faster response. • The cation motion in polymer electrolyte is key for performances of EGOTs.