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

Two-dimensional (2D) AA′_n−1M_nX_3n+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−1M_nX_3n+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 Gy_air⁻¹ cm⁻² under the 10 V bias (0.31 V μm⁻¹), a detection limit as low as 430 nGy_air 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 τ_rise=7.3 ms and τ_fall=22.5 ms. These crystals are promising candidates for the next generation of optoelectronic devices.