Band-Engineerable Ferroelectric 2D CuInP₂S₆ Heterojunctions for Adaptive Visual Contrast

Two-dimensional layered CuInP₂S₆ (CIPS) combines robust room-temperature-switchable ferroelectric polarization with precise control over polarization states, allowing for multiple neuromorphic devices. In this work, we present a band-engineerable ferroelectric CIPS-WS₂/MoS₂ heterostructure, which features polarization-regulated adaptive visual contrast across dynamic illumination conditions. Under bright-light conditions, negative polarization of CIPS induces a bidirectional (ultraviolet) UV/visible response. The UV component triggers negative photoresponse, suppressing background current and thus enhancing contrast. Under low-light conditions, positive polarization of CIPS minimizes dark current, preserving high contrast despite weak signals. Under both conditions, the contrast can be further amplified via synaptic potentiation of the CIPS layer. The device can emulate the UV/vis vision of bees, improving the flower stamen detection rate. In the proposed autonomous driving scenarios, it achieves a high target recognition accuracy under both bright and dim conditions, outperforming conventional static sensors. These results highlight the device's potential for reliable operation in extreme environments. This work demonstrates a hardware-level adaptive vision strategy with broad potential for autonomous systems, robotics, and intelligent sensing applications.