Polarization reversal and ion-electron co-modulation in in-plane anisotropic AgVP2S6 for multimodal image processing.

The recent emergence of quaternary van der Waals layered transition metal phosphorus chalcogenide compounds, which serve as exemplary ionic-electronic coupled semiconductors, has motivated considerable interest in the development of optically modulated in-sensor computing and refreshable neuromorphic devices. Here, we report monoclinic AgVP2S6 crystals featuring quasi-one-dimensional ordering within well-defined zigzag chains, whose pronounced in-plane optical anisotropy arises from the highly asymmetric distribution of the conduction band minimum and valence band maximum along the a- and b-axes. Notably, the anisotropic electrical and optoelectronic responses of AgVP2S6 along the a- and b-axes are attributable to the disparate energy barriers for Ag+ ion migration. By implementing an ionic-electronic co-modulation strategy, we achieve the integration of anisotropic ionic-electronic transport, visible-to-near-infrared spectral response, synaptic plasticity, and advanced image processing capabilities, establishing a versatile platform for next-generation anisotropic optoelectronic devices with applications in neuromorphic computing, autonomous navigation, and multimodal imaging.