Ambipolar Bulk Heterojunction Semiconductor Fibers for High-Performance Neuromorphic Systems

Semiconductor fibers provide a basis for advanced bioelectronic systems, enabling the integration of sensors, logic, and signal processing into flexible, wearable designs. Recent advances in p- and n-type organic semiconductor fibers have enabled the fabrication of complementary organic electrochemical transistors (OECTs) with improved performance, thereby expanding their potential in neuromorphic computing, chemical and biological sensing, and distributed logic circuits for intelligent textiles. However, conventional unipolar fibers remain limited in integrated multifunctional applications because of restricted charge transport characteristics. In this work, ambipolar bulk heterojunction (BHJ) semiconductor fibers were fabricated through a scalable wet-spinning process by blending p- and n-type conjugated polymers under controlled conditions. The optimized BHJ fibers exhibited balanced ambipolar transport, with μC* (mobility × volumetric capacitance) values of 0.81 ± 0.09 F cm^-1 V^-1 s^-1 (n-type) and 0.63 ± 0.05 F cm^-1 V^-1 s^-1 (p-type) in OECT configurations. Complementary logic circuits and organic electrochemical neurons (OECNs) were also demonstrated, showing spiking behavior and achieving classification accuracy of over 83% in sleep state recognition. These results indicate the potential of BHJ semiconductor fibers for integrated neuromorphic computing and fiber-based bioelectronics.