Centimeter‐Sized Single Crystals of Dion‐Jacobson Phase Lead‐Free Double Perovskite for Efficient X‐ray Detection

2D Dion-Jacobson (DJ) phase hybrid perovskites have shown great promise in the photoelectronic field owing to their outstanding optoelectronic performance and superior structural rigidity. However, DJ phase lead-free double perovskites are still a virgin land with direct X-ray detection. Herein, we have designed and synthesized a new DJ phase lead-free layered double perovskite of (HIS)₂ AgSbBr₈ (1, HIS²⁺ = histammonium). Centimeter-sized (18 × 10 × 5 mm³ ) single crystals of 1 are successfully grown via the temperature cooling technique, exhibiting remarkable semiconductive characteristics such as a high resistivity (2.2 × 10¹¹ Ω cm), a low trap state density (3.56 × 10¹⁰ cm^-3 ), and a large mobility-lifetime product (1.72 × 10^-3 cm² V^-1 ). Strikingly, its single-crystal-based X-ray detector shows a high sensitivity of 223 µC Gy^-1 _air cm^-2 under 33.3 V mm^-1 , a low detection limit (84.2 nGy_air s^-1 ) and superior anti-fatigue. As far as we know, we firstly demonstrates the potential of 2D DJ phase lead-free hybrid double perovskite in X-ray detection, showing excellent photoelectric response and operational stability. This work will pave a promising pathway to the innovative application of hybrid perovskites for eco-friendly and efficient X-ray detection.