Dual‐Mode Learning of Ambipolar Synaptic Phototransistor Based on 2D Perovskite/Organic Heterojunction for Flexible Color Recognizable Visual System

Abstract

Artificial intelligence vision systems (AIVSs) with information sensing, processing, and storage functions are increasingly gaining attention in the science and technology community. Although synapse phototransistor (SPT) is one of the essential components in AIVSs, solution‐processed large‐area photonic synapses that can detect and recognize multi‐wavelength light are highly desirable. One of the major challenges in this area is the inability of the available materials to distinguish colors from the visible light to the near‐infrared (NIR) light for single carrier (hole‐only or electron‐only) SPTs owing to lack of cognitive elements. Herein, 2D perovskite/organic heterojunction (PEA2SnI4/Y6) ambipolar SPTs (POASPTs) are developed via solution process. The POASPTs can display dual‐mode learning process, which can convert light signals into postsynaptic currents with excitement/inhibition modes (hole‐transporting region) or inhibition/excitement (electron‐transporting region). The POASPTs exhibit high responsivity to visible light (104 A W−1) and NIR light (200 A W−1), and effectively perform learning and memory simultaneously. The flexible POASPT arrays can successfully recognize the images of different colors of light. This study reveals that the fabricated POASPTs have great potentials in the development of large‐area, high‐efficiency, and low‐cost AIVSs.

A Review on Solution-Processed Organic Phototransistors and Their Recent Developments

“…Very recently, Huang et al reported a synaptic phototransistor (SPT) for artificial intelligence vision systems [174]. In this study, a visual system was developed to colour recognition (Figure 23).…”

Nanostructured perovskites for nonvolatile memory devices

“…16g) and applied it in artificial intelligence vision systems (AIVSs). 204 One unique advantage of the device was that it could respond to multi-wavelength light, unlike most UV-response perovskite-based electronics. In the measurement, this device showed a dual-model learning process, and had the ability of changing light signals into postsynaptic currents with different excitement/inhibition modes due to different dominating carrier transport mechanisms.…”

Bio‐Inspired In‐Sensor Compression and Computing Based on Phototransistors

“…[44,46] Moreover, the IGZO phototransistor successfully simulates the conversion of the human brain memory behavior from short-term memory to long-term memory for various pulse numbers and optical power densities (Figure 2d; Figures S6a-c and S7a-d, Supporting Information). [47,48] These above-stated characteristics allow the array to visualize and sample the visual signals, effectively. To further demonstrate the memory behavior, 25 phototransistors were created and arranged to form a 5 × 5 array to demonstrate this claim (Figure S8, Supporting Information).…”