Aggregation Modulation of Conjugated Polymers by Carbon Dots for Optoelectronic Synaptic Transistors and Artificial Visual Recognition

Developing low-power and highly stable optoelectronic synaptic devices is essential for emulating visual neuromorphic functions. Herein, hydrophobic nitrogen/sulfur-doped carbon quantum dots (N/S-CDs) synthesized via a one-step hydrothermal method effectively promote the enhanced aggregation of conjugated polymer DPPDTT. Meanwhile, benefiting from the abundant surface functional groups and defect states of N/S-CDs, the resulting organic optoelectronic synaptic transistor (OOST) exhibits diverse synaptic behaviors, including linear multibit storage capability and wavelength-dependent synaptic plasticity, with a retention time exceeding 1000 s, a 1.3×10⁶ Ion/Ioff ratio, and an energy consumption of 3 aJ per event. Neuromorphic functionalities such as learning and memorizing QR code patterns, decoding encrypted optical signals, and recognizing handwritten digits with 92.58% accuracy are successfully emulated. This work highlights the critical roles of energy level alignment and defect-mediated charge trapping in N/S-CDs, offering a promising strategy for designing simple, efficient, and stable nonvolatile OOSTs for future artificial visual systems.