The effect of the electrolyte's counter-ion in organic electrochemical transistors is often neglected. the influence of anions (i.e., counter ions) is investigated on organic electrochemical transistors (OECTs) with a PEDOT:PSS-like semiconductor through device simulations. The study examined the effects of mobile anions on OECT performance under two scenarios: when anions are blocked by the semiconductor and when they can penetrate it. In each case, the OECT's ON and OFF states are analyzed. The findings show that when anions can penetrate the semiconductor, the ON/OFF ratio of the OECT remains unchanged while the transconductance significantly increases. In the ON state, the case of blocked anions is observed that the current is predominantly surface-current, whereas it becomes volumetric only when anions can penetrate the semiconductor. Furthermore, the extreme case is explored in which anions remain stationary within the electrolyte. In this scenario, achieving a reasonable ON/OFF ratio necessitates an ion density within the electrolyte that is two orders of magnitude higher than the dopant density of the semiconductor. This work underscores the substantial influence of counter anions on OECT performance, highlighting their critical role in shaping device behavior.

中文翻译：

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揭示电解质的反离子对有机电化学晶体管性能的影响

有机电化学晶体管中电解质反离子的影响常常被忽视。通过器件模拟研究了阴离子（即抗衡离子）对具有 PE​​DOT:PSS 类半导体的有机电化学晶体管 (OECT) 的影响。该研究考察了两种情况下移动阴离子对 OECT 性能的影响：阴离子被半导体阻挡以及阴离子可以穿透半导体。在每种情况下，都会分析 OECT 的开启和关闭状态。研究结果表明，当阴离子可以穿透半导体时，OECT 的开/关比保持不变，而跨导显着增加。在导通状态下，观察到阴离子被阻挡的情况，电流主要是表面电流，而仅当阴离子可以穿透半导体时才变成体积电流。此外，还探讨了阴离子在电解质内保持静止的极端情况。在这种情况下，要实现合理的开/关比，电解质内的离子密度必须比半导体的掺杂剂密度高两个数量级。这项工作强调了抗衡阴离子对 OECT 性能的重大影响，强调了它们在塑造设备行为中的关键作用。