Flexible Multiband Photonic Synapses for Nociceptive Perception and Neuromorphic Computation via Fluorinated InP Quantum Dots

Organic photonic synaptic transistors (OPSTs), emulating biological synaptic behaviors under optical stimulation, serve as essential hardware components for neuromorphic visual systems. To satisfy various demands, state-of-the-art OPSTs typically require multispectral responsiveness that is often pursued by leveraging the excellent optoelectronic properties and solution-processability of quantum dots (QDs). However, this strategy suffers from complex fabrication procedures, limited mechanical flexibility and toxic cadmium/lead compositions in QDs, which raise serious environmental and biosafety concerns. In this work, we demonstrate a fully solution-processed and self-supporting flexible OPST based on environmentally benign indium phosphide (InP) QDs. Through ligand exchange with fluorinated thiols, the QDs demonstrate improved photostability and enhanced energy level alignment with organic semiconductors. Furthermore, the interfacial dipole induced by fluorinated ligands enables long-term charge retention. The resulting QD-OPST devices exhibit broadband excitatory postsynaptic current (EPSC) responses, tunable synaptic plasticity, remarkable mechanical durability and ultralow energy consumption of 0.016 fJ, effectively mimicking cornea-like nociceptor behaviors. In addition, the QD-OPSTs display pronounced color selectivity, enabling blue-feature recognition while suppressing red-green background noise. This study provides a feasible strategy for developing high-performance, eco-friendly, and flexible photonic synapse devices, highlighting great potential for applications in visual perception and brain-inspired computing.