Sensitive and Stable 1D MDAPb₂I₆ Single-Crystal X-ray Detector with Anisotropic Response

Metal halide perovskite single crystals have emerged as promising materials for sensitive X-ray detection due to their large atomic number and superior optoelectronic properties. The widely investigated three-dimensional (3D) perovskites possess isotropic carrier transport properties that can induce lateral signal cross-talk and reduce resolution during X-ray imaging. Besides, the strong ion migration phenomenon causes the fluctuation of dark current and fast device degradation. Herein, we report the growth of centimeter-size, high-quality one-dimensional (1D) MDAPb₂I₆ (MDA = 4,4'-methylenedianiline) single crystals by thermostatic metastable growth and continuous solute replenishment. The 1D crystals exhibit strong anisotropy in carrier transport due to electrostatic shielding of organic chains that separate the octahedral chains. As a result, the X-ray detectors along the c axis show a high sensitivity of 0.65 × 10⁴ μC Gy_air^-1 cm^-2, 1 order of magnitude larger than those along a and b axes, which is potential for suppressing lateral carrier diffusion and thereby signal cross-talk. Moreover, MDAPb₂I₆ single crystals exhibit a high ion migration activation energy (E_a) of 1.27 eV, resulting in a small dark current fluctuation of 6 × 10^-8 nA cm^-1 s^-1 V^-1 and stable photoresponse under high-dose irradiation. Besides, a decent detection limit of 87.5 nGy_air s^-1 is obtained, smaller than the dose rate for practical medical imaging. Our work shows the potential of 1D perovskite single crystals for suppressing lateral carrier diffusion and ion migration, which is instructive for achieving high-resolution and stable X-ray imaging.