Reconfigurable Bidirectional Phototransistors Enabled by Graphene‐Integrated Asymmetric PtTe ₂ /WSe ₂ Van der Waals Heterojunction

Abstract Reconfigurable bidirectional photodetectors based on 2D semimetal/semiconductor heterojunctions have emerged as promising candidates for advanced optoelectronic applications in logic circuits, switchable imaging, and in‐sensor computing platforms. However, dynamics control over Schottky barriers remains challenging due to Fermi‐level pinning effects at metal/2D semiconductor interfaces. This limitation can be mitigated through all‐2D heterojunction designs that enhance Fermi‐level tunability in the channel material. In this approach, the bottom‐contacted PtTe ₂ configuration leverages a screening effect to stabilize the Fermi level, facilitating inversion of the built‐in electric field when paired with the bipolar WSe ₂ channel. Then, integrating multilayer graphene as an asymmetric secondary contact enables gate‐modulation of Schottky barriers at the PtTe ₂ /WSe ₂ heterojunction. This architecture achieves dynamically reversible rectification characteristics, and gate‐switchable bidirectional photoresponse, exhibiting a photovoltaic responsivity of 511 mA W ⁻¹ and a specific detectivity of 4 × 10 ¹⁰ Jones. Furthermore, gate‐tunable half‐wave rectifier circuits have developed for reconfigurability validation, single‐pixel sensing systems, and optoelectronic XNOR, OR, and AND logic gates. The proposed all‐2D heterojunction demonstrates feasible polarity switching capabilities when implemented in on‐chip processing platforms, offering a pathway to subsequent large‐scale, high‐area sensing applications.