Polarized-light photodetectors are the indispensable elements for practical optical and optoelectronic device applications. Two-dimensional (2D) hybrid perovskite ferroelectrics, in which the coupling of spontaneous polarization (P_s) and light favors the dissociation of photo-induced carriers, have taken a booming position within this portfolio. However, polarized-light photodetectors with a low detection-limit remain unexplored in this 2D ferroelectric family. In this work, the high-quality individual crystals of a 2D perovskite ferroelectric, BA₂CsPb₂Br₇ (1, where BA⁺ is n-butylammonium), were used to fabricate ultrasensitive polarized-light detectors. Its unique bilayered structural motif results in quite strong electric and optical anisotropy with a large absorption ratio of α_c/α_a ≈ 3.2 (λ = 405 nm). Besides, the presence of ferroelectric P_s also endows high built-in electric field along the polar c-axis that favors photoelectric activities. Under an extremely low detectable limit of 40 nW/cm², the detector of 1 exhibits a notable dichroism ratio (I_ph^c/I_ph^a ≈ 1.5), a large responsivity of ~39.5 mA/W and a specific detectivity of ~1.2 × 10¹² Jones. Moreover, crystal-based devices of 1 also exhibit a fast response speed (~300 μs) and excellent anti-fatigue merits. This work highlights great potentials of hybrid perovskite ferroelectrics toward polarized-light photodetection.

偏振光探测器是实际光学和光电器件应用中不可或缺的元件。二维 (2D) 混合钙钛矿铁电体，其中自发极化 ( Ps ) 和光的耦合有利于光生载流子的解离，在该产品组合中占据了蓬勃发展的地位_。然而，在这个 2D 铁电体系列中，具有低检测限的偏振光光电探测器仍未得到探索。在这项工作中，二维钙钛矿铁电体 BA ₂ CsPb ₂ Br ₇ ( 1，其中 BA ⁺是n-丁基铵），用于制造超灵敏偏振光探测器。其独特的双层结构基序导致相当强的电学和光学各向异性，具有较大的吸收比α _c / α _a ≈ 3.2 ( λ  = 405 nm)。此外，铁电体Ps_{的存在也赋予了沿极}c轴的高内建电场，有利于光电活动。^{在 40 nW/cm 2}的极低检测限下， 1的检测器表现出显着的二色性比 ( I _ph ^c / I _ph ^a≈ 1.5)，~39.5 mA/W 的大响应度和~1.2 × 10 ¹²琼斯的比检测率。此外，基于晶体的器件1还具有快速响应速度（~300 μs）和出色的抗疲劳优点。这项工作突出了混合钙钛矿铁电体在偏振光光电探测方面的巨大潜力。