Asymmetric Contact van der Waals Ferroelectric Transistors for Self-Powered Multifunctional Artificial Visual System

The development of self-powered artificial visual systems capable of emulating the multifunctionality of the human eye, such as light adaptation, optical memory, and in-sensor computing, is pivotal for next-generation intelligent bionic technologies. In this study, we present a van der Waals ferroelectric field-effect transistor (vdW-FeFET) based on an asymmetric contact α-In₂Se₃/h-BN/CIPS heterostructure, which operates entirely in a self-powered mode. By harnessing the intrinsic opto-ferroelectric coupling of α-In₂Se₃ and the built-in electric fields induced by asymmetric source-drain contact areas, the device exhibits a range of neuromorphic visual behaviors, including visible light sensing and adaptation (405-660 nm), wavelength-dependent color differentiation, and robust optical memory capabilities. The combined effects of photopyroelectric and photothermoelectric mechanisms enable dynamic modulation of the photocurrent, facilitating visual adaptations analogous to biological systems. The device further demonstrates pronounced synaptic characteristics, such as a high paired-pulse facilitation index (∼180%) and memory consolidation from short- to long-term states under repetitive optical stimulation. In particular, pattern recognition is achieved without any external bias, showcasing the potential for autonomous visual signal processing. This work presents a multifunctional, energy-efficient platform for bioinspired vision systems, offering a promising pathway toward neuromorphic computing and next-generation optoelectronic intelligence.