3D‐to‐2D Dimensional Reduction for Exploiting a Multilayered Perovskite Ferroelectric toward Polarized‐Light Detection in the Solar‐Blind Ultraviolet Region

Polarized‐light detection in solar‐blind ultraviolet region is indispensable for optoelectronic applications, whereas new 2D candidates targeted at solar‐blind UV range remain extremely scarce. 2D hybrid perovskite ferroelectrics that combine polarization and semiconducting properties are of increasing interest. Here, using the 3D‐to‐2D dimensional reduction of CH 3 NH 3 PbCl 3 , we designed a multilayered hybrid perovskite ferroelectric, (CH 3 CH 2 NH 3 ) 2 (CH 3 NH 3 ) 2 Pb 3 Cl 10 , which shows spontaneous polarization and a high Curie temperature (390 K) comparable with that of BaTiO 3 (393 K). The wide band gap (ca. 3.35 eV) and anisotropic absorbance stemming from its intrinsic 2D motif, greatly favor its polarization‐sensitive activity in UV region. The device displays excellent polarization‐sensitive behavior under 266 nm, along with a large dichroic ratio (ca. 1.38) and high on/off current ratio (ca. 2.3×10 3 ).