The high transconductance gm of organic electrochemical transistors (OECTs) has received widespread attention and made OECTs a valid candidate for wearable sensor systems. However, the large transconductance is often accompanied by large switching time constants, τ, making the transconductance an imperfect benchmark. For a fair assessment, the ratio of transconductance to switching time constant has to be considered instead of any single parameter in isolation. One approach put forward to optimize OECTs is a vertical design, in which the channel length can be scaled into the sub‐micrometer regime. Here, a new vertical device geometry is proposed, in which the active volume of the mixed conductor is confined to a small cavity between source and drain, yielding excellent performance and reproducibility. It is shown that this approach yields optimized ratios instead of maximized transconductance only. However, this scaling is effective only in a small range of device dimensions and requires careful optimization of the device to not be limited by parasitic effects such as excess volume of the mixed conductor or parasitic series resistances. Overall, the design considerations discussed here provide new guidelines to optimize OECTs, not only for high transconductance but for operation at high frequencies as well.

中文翻译：

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立式有机电化学晶体管跨导和速度之间的权衡

高跨导G米有机电化学晶体管（OECT）的研究受到了广泛的关注，并使 OECT 成为可穿戴传感器系统的有效候选者。然而，大的跨导通常伴随着大的开关时间常数 τ，使得跨导成为一个不完美的基准。为了公平评估，必须考虑跨导与开关时间常数的比率，而不是孤立的任何单个参数。优化 OECT 的一种方法是垂直设计，其中通道长度可以缩放到亚微米范围。这里，提出了一种新的垂直器件几何结构，其中混合导体的有效体积被限制在源极和漏极之间的小空腔内，从而产生优异的性能和再现性。结果表明，这种方法可以产生优化的比率，而不仅仅是最大化跨导。然而，这种缩放仅在小范围的器件尺寸中有效，并且需要仔细优化器件，以免受到寄生效应的限制，例如混合导体的体积过大或寄生串联电阻。总的来说，这里讨论的设计考虑因素为优化 OECT 提供了新的指导方针，不仅针对高跨导，而且还针对高频操作。