Centimeter‐Sized Single Crystal of Two‐Dimensional Halide Perovskites Incorporating Straight‐Chain Symmetric Diammonium Ion for X‐Ray Detection

Two‐dimensional (2D) AA′n−1MnX3n+1 type halide perovskites incorporating straight‐chain symmetric diammonium cations define a new type of structure, but their optoelectronic properties are largely unexplored. Reported here is the synthesis of a centimeter‐sized AA′n−1MnX3n+1 type perovskite, BDAPbI4 (BDA=NH3C4H8NH3), single crystal and its charge‐transport properties under X‐ray excitation. The crystal shows a staggered configuration of the [PbI6]4− layers, a band gap of 2.37 eV, and a low trap density of 3.1×109 cm−3. The single‐crystal X‐ray detector exhibits an excellent sensitivity of 242 μC Gyair−1 cm−2 under the 10 V bias (0.31 V μm−1), a detection limit as low as 430 nGyair s−1, ultrastable response current, a stable baseline with the lowest dark current drift of 6.06×10−9 nA cm−1 s−1 V−1, and rapid response time of τrise=7.3 ms and τfall=22.5 ms. These crystals are promising candidates for the next generation of optoelectronic devices. Crystal clear: Reported here is the synthesis of a centimeter‐sized AA′n−1MnX3n+1 type perovskite, BDAPbI4 (BDA=NH3C4H8NH3), single crystal and its charge‐transport properties under X‐ray excitation. The crystal shows a staggered configuration of the [PbI6]4− layers, a band gap of 2.37 eV, and a low trap density of 3.1×109 cm−3. These crystals are promising candidates for the next generation of optoelectronic devices.