Neuromorphic computing is an emerging area with prospects to break the energy efficiency bottleneck of artificial intelligence (AI). A crucial challenge for neuromorphic computing is understanding the working principles of artificial synaptic devices. As an emerging class of synaptic devices, organic electrochemical transistors (OECTs) have attracted significant interest due to ultralow voltage operation, analog conductance tuning, mechanical flexibility, and biocompatibility. However, little work has been focused on the first-principal modeling of the synaptic behaviors of OECTs. The simulation of OECT synaptic behaviors is of great importance to understanding the OECT working principles as neuromorphic devices and optimizing ultralow power consumption neuromorphic computing devices. Here, we develop a two-dimensional transient drift–diffusion model based on modified Shockley equations for poly(3,4-ethylenedioxythiophene) (PEDOT)-based OECTs. We reproduced the typical transistor characteristics of these OECTs including the unique non-monotonic transconductance–gate bias curve and frequency dependency of transconductance. Furthermore, typical synaptic phenomena, such as excitatory/inhibitory postsynaptic current (EPSC/IPSC), paired-pulse facilitation/depression (PPF/PPD), and short-term plasticity (STP), are also demonstrated. This work is crucial in guiding the experimental exploration of neuromorphic computing devices and has the potential to serve as a platform for future OECT device simulation based on a wide range of semiconducting materials.

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This work proposes a method to prepare a K+-intercalated P2-Na x Cu0.2Mn0.8O2 cathode material for sodium-ion batteries. By calcining a P3-K x Cu0.2Mn0.8O2 in a Na+ rich environment, a K+-intercalated Na x Cu0.2Mn0.8O2 cathode with a stable P2 phase and high K+ content can be obtained. The intercalation of K+ enlarges the interlayer distance and improves the diffusion of Na+, thus enhancing the sodium-storage performance of the material. High capacity (155.1 mAh g–1 at 1 C), high rate performance (71.2 mAh g–1 at 10 C), and good stability (78.18% after 200 cycles at 1 C) can be achieved. It is found that K+ can be well-preserved inside the material during the cycling process. Hence, the enhancement caused by K+ is more evident than other similar materials prepared by conventional methods during the charge and discharge cycles.

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