Intrinsic Strong Linear Dichroism of Multilayered 2D Hybrid Perovskite Crystals toward Highly Polarized‐Sensitive Photodetection

Abstract Linear dichroism of 2D materials is brought into practical operation of polarized light detection; currently, organic–inorganic 2D hybrid perovskites with the linear dichroic nature offers immense potentials within this portfolio. Here, a newly tailored 2D hybrid perovskite, ( i BA) 2 (MA)Pb 2 I 7 ( 1 , where MA + is methylammonium and i BA + is n ‐isobutylammonium) is investigated, adopting a highly anisotropic bilayered perovskite motif that results in strong crystallographic‐dependence of linear dichroism. Both the absorption spectra (300–650 nm) and polarized‐sensitive activities of 1 exhibit the distinctive anisotropic characteristics. Consequently, based on this intrinsic linear dichroism, crystal‐based photodetectors of 1 show remarkable polarized‐light detecting behaviors, including quite fast response time (≈300 µs), notable photocurrent on/off ratio (>10 3 ) and large dichroic ratios ( I pb / I pc ≈ 1.20 at 520 nm, 1.23 at 637 nm). Such figure‐of‐merits are comparable to those of the conventional GeSe nanoflakes (the linearly dichroic ratio of ≈1.09 at 532 nm), revealing the great potentials of 1 for the future polarized photodetection. As an innovative work, the intrinsic anisotropy and prominent linear dichroism of 1 , together with the structural flexibility, opens up a promising avenue for exploring new candidates for the 2D polarized optoelectronic applications.