Ultralow Light‐Power Consuming Photonic Synapses Based on Ultrasensitive Perovskite/Indium‐Gallium‐Zinc‐Oxide Heterojunction Phototransistors

The brain‐inspired neuromorphic parallel computing has become one of the most promising technologies for efficient information processing by overcoming the von Neumann bottleneck of sequential operations. Synapses transmit information among neurons and act as the basic component in neuromorphic computing platforms. Despite the rapid advances in developing artificial synapses, most synaptic devices function electronically and thus numerous merits for photonics such as visual/imaging information processing, less corsstalk, and fast response, have to be compromised. Herein, a light‐stimulated synaptic device (photonic synapses) based on perovskite/In‐Ga‐Zn‐O heterojunction phototransistor is reported. The combination of high‐efficiency light absorber, high‐mobility channel, and heterojunction device architecture leads to efficient photon‐to‐electron conversion and intrinsic high‐gain mechanism for such light‐stimulated synapses. As a result, high performance photonic synapses are obtained with the basic functions of excitatory postsynaptic current (EPSC), paired‐pulse facilitation (PPF), and short‐term memory to long‐term memory conversion (STM‐LTM). Importantly, owing to the ultrasensitive photodetection characteristics, the light power consumption of such photonic artificial synapse can be as low as 2.6 picojoule. This study proposes a simple, efficient, and industry‐compatible device concept providing the photosensitive synapses for photonic neural networks by combining the merits of appropriate materials and device architecture. Ultrasensitive perovskite/Indium‐Gallium‐Zinc‐Oxide heterojunction phototransistors are designed and fabricated. The lowest detectable light power density can be as low as 0.52 nw cm‐2 and the basic functions of light‐stimulated artificial synapses have been realized. In particular, the light power consumption per synaptic event can be reduced to