Bias-Switchable Photodetection and Photosynapse Dual-Functional Devices Based on 2D Perovskite/Organic Heterojunction for Imaging-to-Recognition Conversion.

Optoelectronic devices with imaging and recognition capabilities are crucial for developing artificial visual system (AVS). Bias-switchable photodetection and photosynaptic devices have been developed using 2D perovskite oxide/organic heterojunctions. This unique structure allows for modulated carrier dynamics under varied bias conditions, enabling the devices to function as photodetectors without bias and as photosynapses with bias. At zero bias, the device achieves high responsivity (≈0.36 A W at 320 nm) and rapid response speed (0.57 s). Under a -0.5 V bias, it exhibits persistent photoconductivity (PPC), resulting in neuromorphic synaptic behaviors with a paired-pulse facilitation (PPF) index exceeding 300%. Moreover, an 8 × 8 sensor array demonstrates image sensing and memory capabilities, showing in situ enhanced imaging when switching the bias from 0 to -0.5 V, and over 200 s of image memory. The image processing and recognition abilities are further explored by constructing an AVS using a 28 × 28 device array combined with an artificial neural network (ANN). The adjustable synaptic weight under different reverse biases allowed for optimized simulated recognition, achieving an accuracy of 92% after 160 training epochs. This work presents a novel method for creating dual-functional photodetection and photosynaptic devices, paving the way for a more integrated and efficient AVS.