Polar Bilayered Dion–Jacobson Hybrid Perovskite Single Crystal with Bulk Photovoltaic Effect for Self-Driven X-ray–Ultraviolet–Visible Photodetection

Polar two-dimensional (2D) multilayered hybrid perovskites (HPs) have emerged as an outstanding class of self-driven photodetection materials. However, the current market for self-driven photodetection is almost dominated by Ruddlesden–Popper (RP) HPs. Up to now, most of the Dion–Jacobson (DJ) HPs reported have crystallized in the centrosymmetric space group, so the photodetection based on this needs to be driven by external circuits, which not only increases the cost of the device but also limits the flexibility and photostability of the device. Therefore, constructing a broadband self-driven photodetection system that integrates sensing and energy supply in DJ HPs is the development trend of the future. Herein, we constructed two new polar DJ HPs (1,3-BMACH)(MA)Pb 2 I 7 and (1,3-BMACH)(FA)Pb 2 I 7 (1,3-BMACH is 1,3- bis (aminomethyl)cyclohexane, MA is methylammonium, FA is formamidinium) using cyclic diammonium as the spacer and MA, FA as perovskitizers, respectively. Due to the larger size of FA than MA, the elongation of Pb–I bond length results in (1,3-BMACH)(FA)Pb 2 I 7 ( λ cutoff = 630 nm) having a narrower light absorption range than (1,3-BMACH)(MA)Pb 2 I 7 ( λ cutoff = 650 nm). The devices based on (1,3-BMACH)(MA)Pb 2 I 7 single crystals can achieve high-efficiency broadband self-driven photodetection from the X-ray and ultraviolet to visible-light region. The self-driven detection for X-ray has a high sensitivity (199 μC Gy air –1 cm –2 ) and a low detection limit (106 nGy air s –1 ). Especially, the detectivity and responsivity of the device can reach 4.82 × 10 10 Jones and 0.58 mA/W under zero bias at 405 nm laser illumination. Meanwhile, (1,3-BMACH)(MA)Pb 2 I 7 and (1,3-BMACH)(FA)Pb 2 I 7 also exhibit reversible thermochromic transformation from light red to dark red.