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Organic Electrochemical Transistors are versatile sensors that became essential for the field of organic bioelectronics. However, despite their importance, an incomplete understanding of their working mechanism is currently precluding a targeted design of Organic Electrochemical Transistors and it is still challenging to formulate precise design rules guiding materials development in this field. Here, it is argued that current capacitive device models neglect lateral ion currents in the transistor channel and therefore fail to describe the equilibrium state of Organic Electrochemical Transistors. An improved model is presented, which shows that lateral ion currents lead to an accumulation of ions at the drain contact, which significantly alters the transistor behavior. Overall, these results show that a better understanding of the interface between the organic semiconductor and the drain electrode is needed to reach a full understanding of Organic Electrochemical Transistors. 

Research in Organic Permeable Base Transistors (OPBTs) has led to a significant increase in their performance. However, despite this progress, understanding of the working mechanism of OPBTs is still limited. Although first numerical models of OPBTs are able to describe the switching mechanism of OPBTs correctly, they neglect currents injected at the base electrode, which leads to unrealistically low off-currents and high ON/OFF ratios. Here, a tunneling model is developed that is capable of describing injection of charges through a thin oxide layer formed around the base electrode of OPBTs. With the help of this injection model, the performance of the base-collector diode of OPBTs is discussed. In particular, the model is used to explain the reduction in backward currents due to an exposure to ambient air by an increase in the thickness of the oxide layer. Furthermore, the tunnel model is used to show that the reduction in backward currents of the base-collector diode leads to a decrease in off-currents of complete OPBTs, which in turn leads to an increase in their ON/OFF ratio. 

Abstract Faux‐hawk fullerenes are promising candidates for high‐performance organic field‐effect transistors (OFETs). They show dense molecular packing and high thermal stability. Furthermore, in contrast to most other C₆₀derivates, functionalization of the fullerene core by the fluorinated group C₆F₄CF₂does not increase their lowest unoccupied orbital position, which allows the use of air‐stable molecular n‐dopants to optimize their performance. The influence of n‐doping on the performance of OFETs based on the faux‐hawk fullerene 1,9‐C₆₀(cyclo‐CF₂(2‐C₆F₄)) (C₆₀FHF) is studied. An analytic model for n‐doped transistors is presented and used to clarify the origin of the increase in the subthreshold swing usually observed in doped OFETs. It is shown that the increase in subthreshold swing can be minimized by using a bulk dopant layer at the gate dielectric/C₆₀FHF layer instead of a mixed host:dopant layer. Following an optimization of the OFETs, an average electron mobility of 0.34 cm² V⁻¹ s⁻¹, a subthreshold swing below 400 mV dec⁻¹for doped transistors, and a contact resistance of 10 kΩ cm is obtained, which is among the best performance for fullerene based n‐type semiconductors.