Room Temperature Anisotropic Photoresponse in Low‐Symmetry Van der Waals Semiconductor CrPS ₄

ABSTRACT The crystalline and optical anisotropy of low‐symmetry 2D materials can enable strong dichroic responses, enhancing polarization contrast for photonic and optoelectronic devices. Here, we unveil pronounced optical and optoelectronic anisotropy in chromium thiophosphate (CrPS 4 ) arising from the strong coupling between light polarization and its intrinsic crystal symmetry. Linearly polarized reflectivity and scanning photocurrent measurements in the 1.37–2.48 eV range reveal a robust dichroic response. The linear dichroism in reflection (RLD) reaches 50%, while in photocurrent (PCLD) it increases to 60%, with a sign reversal of the RLD between 1.6–1.8 eV, enabling strong narrow‐band polarization contrast at room temperature. We attribute these anisotropic responses to the interaction between polarized light and d ‐orbital T 1 and T 2 transitions. Spatially resolved photocurrent mapping further shows that the photocurrent is strongly dependent on the crystallographic axis: a threefold enhancement is obtained along the b ‐axis compared to the a ‐axis, yielding a clear 180 modulation of photoresponse across different contact orientations. Together, our findings establish CrPS 4 as a highly anisotropic 2D semiconductor with strong linear dichroism and polarization‐sensitive photoresponse at room temperature. These characteristics highlight CrPS 4 as a promising platform for narrow‐band polarized photodetectors, anisotropic photo‐transport, and future 2D spintronic and magneto‐optical devices.