Centimeter‐sized Single Crystal of Two‐Dimensional Halide Perovskites Incorporating Straight Chain Symmetric Diammonium Ion for Efficient 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 that holds potential of both highly efficient charge transport and high environmental stability. Unfortunately, their optoelectronic properties are largely unexplored and there is lack of high quality single crystals in large dimension for practical application. Here, we ventured into synthesizing centimeter-sized AA'n-1MnX3n+1 type perovskite BDAPbI4 (BDA = NH3C4H8NH3) single crystal and reported its charge transport properties under X-ray excitation. The crystals were grown via a modified temperature crystallization method. It is found that the crystal shows a staggered configuration of the [PbI6]4- layers, a bandgap 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, ultra-stable 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. The effective synthesis method and excellent charge transport properties of AA'n-1MnX3n+1 type 2D perovskite single crystals make them promising candidates for the next generation of optoelectronic devices.