Highly‐Anisotropic Dion–Jacobson Hybrid Perovskite by Tailoring Diamine into CsPbBr3 for Polarization‐Sensitive Photodetection

2D materials with inherent attributes of structural anisotropy have been well applied in the field of polarization-sensitive photodetection. However, to explore new 2D members with strong polarized-light responses still remains a challenge. Herein, by alloying diamine molecule into the 3D prototype of CsPbBr3 , a new Dion-Jacobson (DJ) type 2D perovskite of (HDA)CsPb2 Br7 (1, where HDA2+ is 1,6-hexamethylenediammonium), containing both inorganic Cs metal and organic cations is designed. The natural anisotropy characteristics of 1 are solidly elucidated by analyzing crystal structure, electric conductivity, and optical properties. Strikingly, distinct polarization-sensitive responses are observed in 1, owing to its strong anisotropy of optical absorption (the ratio of αc /αb ≈ 2.2). Consequently, crystal-based detectors of 1 exhibit fascinating photo-activities to polarized-light, including high detectivity (1.5 × 109 Jones), large dichroism ratio (Iphc /Iphb ≈ 1.6) and fast responding rate (200 µs). All these polarization-sensitive performances along with intriguing phase stability make 1 a potential candidate for polarized-light detection. This work paves a pathway toward new functionalities of DJ-type 2D hybrid perovskites for their future optoelectronic device applications.