Ultraviolet Photodetection with Low Detection Limit Using Inch‐Sized Two‐Dimensional Hybrid Perovskite Crystal

Abstract Ultraviolet (UV) photodetection is widely used in different fields, among which the photodetection with low detection limit has attracted strong interest due to broad applications in various fields including military security, medical diagnosis, and chemical analysis. Recently, two‐dimensional (2D) hybrid perovskites are promising candidates for UV photodetection owing to their superior semiconducting properties and solution accessibility. Here, UV photodetection with low detection limit is successfully realized by using high‐quality 2D hybrid perovskite single crystals, (BA)₂PbBr₄ (1, BA = C₄H₉NH₃⁺). Grown via a delicate solution method, a high‐quality single crystal of 1 as large as 35 × 15 × 1 mm³ is obtained with a low trap density of ≈10¹⁰ cm⁻³, and used to fabricate photodetectors hence exhibiting an ultra‐low dark current of 6.11 × 10⁻¹³ A. The detector exhibits a considerable on/off ratio of ≈10⁴, an impressive detectivity up to 2.06 × 10¹² Jones, and a responsivity of 16.9 mA W⁻¹. Notably, due to the high‐crystalline quality and low dark current of 1, the device shows remarkable photoresponse even under an extremely weak illumination of 80 nW cm⁻² at the UV region. This work provides a promising candidate for sensitive UV photodetection and high‐performance photodetectors.