A Self‐Powered Ultrafast Polarization‐Sensitive Multifunctional Photodetector Driven by Phonon Anisotropy in a PtSe 2 /MoSe 2 Heterostructure

Polarization‐sensitive photodetectors (PSPDs) have attracted significant interest due to their ability to detect both the polarization state and intensity of light, thereby increasing information dimensionality for compact remote sensing, imaging, and communication systems. Conventional polarization‐sensitive detectors rely on external polarization optical components, resulting in bulky device structures, complex architectures, and high cost. Herein, we report a self‐powered PSPD based on a PtSe 2 /MoSe 2 van der Waals heterostructure. The semimetal/semiconductor integration enables broadband photoresponse spanning 400‐1200 nm with excellent polarization sensitivity. Angle‐resolved polarized Raman spectroscopy confirms that interlayer coupling arising from heterostructure formation enhances phonon vibrational anisotropy, leading to stronger optical anisotropy compared to bare PtSe 2 . A remarkable polarization ratio of ∼4.3 is obtained under self‐bias operation. Efficient interlayer charge transport results in ultrafast response times of 68/66 µs at zero bias and 6/6 µs under a 5 V bias. Furthermore, the photodetector delivers a self‐biased responsivity of 0.74 mA W −1 and a detectivity of 4.79 × 10 9 Jones. These results highlight the promise of two‐dimensional transition metal dichalcogenide (TMDC) heterostructures for next‐generation multidimensional imaging and integrated optoelectronic technologies.