Tunable plasticity and multilevel photo-memory enabled by type-II heterojunctions in 2D nanosheet-based organic optical synapses

Abstract The rapid development of the Internet of Things is driving advances in neuromorphic photonic computing systems that leverage light for highly efficient and parallel information processing. Note that to achieve neuromorphic computing with artificial optical synapses, tunable synaptic plasticity and photo-memory functions enabled by direct optical modulation are essential. In this study, we design an organic optical synaptic device with a two-dimensional (2D) metal oxide nanosheet as the charge storage layer, demonstrating bimodal synaptic plasticity and multilevel photo-memory. The precise layer-by-layer liquid deposition technology enables direct integration of 2D Cs 2.7 W 11 O 35 1.3− nanosheet films with controllable thickness into the device for charge storage. Through interfacial band engineering, a type-II heterojunction is established between the organic semiconductor channel and the inorganic nanosheet, enabling gate-voltage-free photogenerated charge transfer and storage. Under optical modulation, the device exhibits tunable synaptic behaviors ranging from short- to long-term plasticity and a multilevel photo-memory capability with a retention time of 10 3 s. Then, we confirm the potential of the synaptic device for highly efficient neuromorphic computing, demonstrating a recognition capability with a high accuracy of 97.8%. Therefore, our device sheds new light on the development of optical computing systems.