Flexible Solution-Processable Black-Phosphorus-Based Optoelectronic Memristive Synapses for Neuromorphic Computing and Artificial Visual Perception Applications.

Being renowned for operating with visible-light pulses and electrical signals, optoelectronic memristive synaptic devices have excellent potential for neuromorphic computing systems and artificial visual information processing. Here, a flexible back-end-of-line-compatible optoelectronic memristor based on a solution-processable black phosphorus/HfO bilayer with excellent synaptic features, toward biomimetic retinas is presented. The device shows highly stable synaptic features such as long-term potentiation (LTP) and long-term depression (LTD) for repetitive 1000 epochs, having 400 conductance pulses, each. The device presents advanced synaptic features in terms of long-term memory (LTM)/short term memory (STM), as well as learning-forgetting-relearning when visible light is induced on it. These advanced synaptic features can improve the information processing abilities for neuromorphic applications. Interestingly, the STM can be converted into LTM by adjusting the intensity of light and illumination time. Using the light-induced characteristics of the device, a 6 × 6 synaptic array is developed to exhibit possible use in artificial visual perception. Moreover, the devices are flexed using a silicon back-etching process. The resulting flexible devices demonstrate stable synaptic features when bent down to 1 cm radius. These multifunctional features in a single memristive cell make it highly suitable for optoelectronic memory storage, neuromorphic computing, and artificial visual perception applications.