Multiphysics modelling and interface optimization of PEDOT:PSS OECTs for stable and sensitive biosensing

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Chinese explanation / 中文解读

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Original abstract

The work presents a detailed analytical and experimental study of the interface analysis of Organic Electrochemical Transistors (OECTs) used for advanced biosensing applications. The focus is on understanding how the gate–electrolyte and channel–electrolyte interfaces affect the overall performance of device. To explain these effects, we used the Poisson–Boltzmann, Nernst–Planck, and Nernst equations to trace the ion-induced doping and de-doping behaviour within PEDOT:PSS layers. Here, we used finite-element simulations to study changes in charge mobility and the electrical double layer, which show excellent agreement with experimental observations of transconductance and saturation current. Devices were fabricated using carbon gates modified with platinum nanoparticles and PEDOT:PSS formulations that were carefully tuned for electrical performance. These OECTs demonstrate a high conductivity of about 600 S cm⁻ 1 . Under continuous pulsed bias operation (V G pulsed between 0 V and -1.0 V at 0.1 Hz, ambient conditions), the devices maintain stable operation for more than 500 h with ensemble-averaged drain current degradation of 13.5% and transconductance degradation of 16.0% at the 500-h time point, following first-order kinetics with a time constant of 1200 ± 40 h. A diverse transition from percolation-based to bulk transport behaviour was noticed at a film thickness of around 200 nm. The most stable and sensitive performance was achieved when the gate voltage ranged from − 0.5 to − 1.0 V. Quantitative validation comparing simulated and experimental transfer characteristics from 35 devices yields a Pearson correlation coefficient R 2 = 0.987, root mean square error of 2.8 μA, and 94.2% of data points falling within ± 6% relative error. The results provide mechanistic insight into interface-controlled electrochemical gating and offer practical guidelines for the design of high-performance OECT biosensors and organic bioelectronic devices.

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