Lead-Free Cs₃Bi₂I₉ Microplates/P3HT Heterojunction for Low-Power Artificial Optoelectronic Synapse

Inspired by the human brain, neuromorphic devices hold the potential to overcome the limitations of the traditional von Neumann architecture. Synapses serve as the core component of neuromorphic devices, which act as the fundamental units for signal conversion. In particular, artificial optoelectronic synapses with color perception capabilities offer significant advantages in multicolor image sensing and visual simulation. In this work, we demonstrate a Cs₃Bi₂I₉ microplate/poly(3-hexylthiophene) (P3HT) heterojunction (CPH) as an ecofriendly and stable optoelectronic synaptic device. The device exhibits typical synaptic behaviors under optical stimulation, including excitatory postsynaptic current, paired-pulse facilitation with a maximum index of about 190%, and controllable transition from short-term to long-term memory. Notably, the CPH synapse achieves low power consumption (<90 fJ per synaptic event), outperforming traditional complementary metal oxide semiconductor-based circuits. Furthermore, the device demonstrates multi-wavelength response capabilities, enabling dual-wavelength perception and preprocessing. Our work provides a sustainable and high-performance alternative for neuromorphic vision systems, paving the way toward environmentally benign synaptic hardware.