Architecture‐Engineered PdSe 2 /SnS 2 /MoS 2 van der Waals Heterostructures for Self‐Powered Photodetection and Programmable Optoelectronic Logic

High‐performance photodetectors for low‐light imaging and high‐speed information processing require high responsivity, high specific detectivity, fast response, and ultralow power consumption enabled by minimal dark current. Although 2D van der Waals heterojunctions can suppress dark current and promote carrier separation via built‐in electric fields, most reported devices still rely on external bias, limiting their application in energy‐efficient integrated systems. Moreover, integrating self‐powered photodetection with programmable optoelectronic logic in a single device remains challenging. Here, we report a vertical trilayer vdW heterojunction phototransistor based on PdSe 2 /SnS 2 /MoS 2 with synergistic functionality. By strengthening the built‐in electric field and optimizing interfacial energy‐level alignment, this architecture suppresses the dark current to the picoampere level while bringing the ideality factor close to unity (η ≈ 1). The device operates in a fully self‐powered mode, achieving a high responsivity of 654 mA W −1 and a specific detectivity of 5.4 × 10 12 Jones under 638 nm illumination—surpassing most previously reported PdSe 2 ‐based self‐powered photodetectors. Beyond photodetection, gate‐voltage modulation enables switchable multistable output states, thereby seamlessly integrating self‐powered sensing with programmable optoelectronic logic in a single device. This work establishes a viable device paradigm for low‐power, highly integrable visible and near‐infrared optoelectronic logic systems.