Centimeter-level double perovskite single crystals with strong interlaminar hydrogen bonds for high-performance X-ray detection†

Ruddlesden–Popper (RP) hybrid perovskites hold great potential for X-ray detection, while the inherent van der Waals gap hinders the preparation of large single crystals. Therefore, reducing the interlaminar energy gap in 2D RP-type perovskites is crucial for exploiting high-performance crystal-based X-ray detectors. We here present a new 2D RP-type double perovskite, (t-ACH)₄AgBiI₈·H₂O (1, t-ACH = 4-aminomethyl-1-cyclohexane carboxylate), of which the intercalated carboxylate spacers form strong interlaminar O–H⋯O hydrogen bonds and favor the elimination of the van der Waals energy gap. This enhanced interlaminar connection in its quasi-2D motif facilitates the growth of large single crystals. As expected, bulk high-quality single crystals of 1 with a centimeter size up to 17 × 12 × 8 mm³ were facilely obtained, which exhibit notable semiconductor properties of low trap density (∼6.57 × 10¹⁰ cm⁻³) and large mobility-lifetime (∼0.77 × 10⁻³ cm² V⁻¹) in the direction vertical to the (−100) plane. Particularly, the single crystal-based detector of 1 shows prominent performance in X-ray detection, including a low dark current drift of 1.97 × 10⁻⁷ nA cm⁻¹ s⁻¹ V⁻¹, a high sensitivity of 3221.6 μC Gy_air⁻¹ cm⁻², and a low detection limit of 12 nGy_air s⁻¹. The figure-of-merit of detection sensitivity is approximately 180 times than the commercial a-Se X-ray detectors. This intercalation of strong O–H⋯O hydrogen bonds reduces the van der Waals gap in 2D RP-type perovskites, which serves as an effective strategy to explore new eco-friendly perovskites for high-performance photoelectric applications.