Photovoltaic Polarity‐Switching Optoelectronic Device Based on MoS 2 /TiS 3 Heterostructures for Multifunctional Operation

Van der Waals (vdW) heterojunctions of 2D materials have emerged as promising platforms for next‐generation optoelectronic devices, owing to their tunable band alignments and unique physical properties. However, achieving high‐performance, self‐powered, and multifunctional device operation remains a significant challenge. This study explores the interface properties and multifunctional capabilities of MoS 2 /TiS 3 heterostructures. Micro‐angle‐resolved photoemission spectroscopy (micro‐ARPES) reveals a substantial interlayer charge transfer of ≈400 meV from MoS 2 to TiS 3 , indicative of pronounced band bending and strong interfacial coupling, key enablers for self‐powered function. The resulting device operates in a self‐powered mode and exhibits reversible photovoltaic polarity switching as a function of light intensity, with tunable detectivity ranging from −5.78 × 10 11 Jones to 3.83 × 10 11 Jones and rapid response times within 1 millisecond. Remarkably, the MoS 2 /TiS 3 heterostructures also demonstrate advanced functionalities such as multi‐logic encoding, communication, and cryptographic imaging, enabled by simultaneous control over gate voltage, laser intensity, and light polarization. These findings underscore the potential of layered transition metal chalcogenide‐based heterostructures as a versatile and powerful platform for high‐performance, multifunctional optoelectronic, and photonic applications.