Dopant-Induced Charge-Trapping Synaptic Transistors via Nanoscale Patterning

Conjugated polymer-based organic neuromorphic systems are great interest due to their highly tunable synaptic plasticity, which can be optimized via chemical doping. Charge trapping and detrapping is essential for emulating synapse functions, but it typically reduces retention current and causes unstable threshold voltage shift, affected by interfacial defects and moisture at the semiconductor–dielectric interface [1,2]. Herein, we report solution-processed CTSs fabricated by blending a p-type conjugated polymer with a small amount of n-type dopant to induce charge trapping and synaptic behavior. Without additional polarization or trapping layers, the dopant molecules form trap sites within the polymer matrix, resulting in effective charge storage. To enhance charge trapping and device stability, nanoscale patterning CSTs (n-CSTs) was introduced to align polymer backbones, improve π–π stacking, facilitate charge transport, and minimize interfacial defects, achieving stable and reproducible performance. The n-CSTs exhibited essential synaptic behaviors such as EPSC, PPF, and STDP, mimicking biological synaptic plasticity. Furthermore, an ANN model based on the LTP/LTD curve characteristics of the n-CSTs was implemented for handwritten digit recognition using the MNIST dataset, achieving 94% accuracy. These results demonstrate that low-concentration n-type doping with nanoscale patterning is a simple strategy in neuromorphic applications.
Acknowledgement
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS2022NR071808) and partially this research was supported by Korea Basic Science Institute (National research Facilities and Equipment Center) grant funded by Ministry of Education (grant No. 2022R1A6C101B738).
References
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2. Ling, K., Li, K., Zhang, W. & Liu, X, Adv. Optical Mater, 11, 2202456 (2023).