Ligand‐Assisted Growth of 2D Perovskite Single Crystal for Highly Sensitive X‐Ray Detectors

Abstract The emerging 2D layered perovskites have promising optoelectronic properties, good intrinsic stability and reduced ion migration, making them effective for detecting X‐ray radiation. However, their application is constrained by poor out‐of‐plane carrier transport. In this study, inch‐sized high‐quality CsPb 2 Br 5 layered single crystals (SCs) are developed using an organic ligand‐assisted solution process. By modifying the surface energy, the anisotropy of crystal growth is conquered, resulting in CsPb 2 Br 5 SCs with sufficient thickness for X‐ray detection. Importantly, this modification significantly enhanced the crystal quality as the grown CsPb 2 Br 5 SCs exhibited longer photoluminescence lifetime and smaller trap density. Notably, the CsPb 2 Br 5 SCs demonstrate unprecedented out‐of‐plane carrier transport, achieving a high carrier mobility‐lifetime product of 2.53 × 10 −2 cm 2 V −1 . This can be attributed to the small interlayer distance and the strong interlayer force of Cs─Br bonding. Furthermore, CsPb 2 Br 5 SCs possess other intriguing attributes for X‐ray detection, including high bulk resistivity and outstanding thermal stability. These advantageous properties enable high‐performance vertical‐structure X‐ray detection with a superior sensitivity of up to 8865.6 µC Gy air −1 cm −2 and a low detectable dose rate of 12.7 nGy air s −1 . Additionally, CsPb 2 Br 5 SCs exhibit high spatial resolution in X‐ray imaging and exceptional thermal stability, making them promising candidates for nondestructive determination.