Two-dimensional Ruddlesden–Popper perovskite microcrystal photodetectors with high detectivity for ultra-weak light detection

Abstract

Strong light absorption capabilities, excellent semiconductor properties, and enhanced humidity and light stability have led to the rapid development of two-dimensional (2D) organic–inorganic metal halide perovskites in the field of light detection. However, so far, the research on weak light detection of 2D perovskite is insufficient, and its detection limit needs to be further broken. Here, high-quality (C₆H₅CH₂CH₂NH₃, PEA)₂PbBr₄ perovskite single crystals with low defect density are prepared. Lateral photodetectors based on this perovskite single crystal demonstrate stable photoresponse under ultra-weak ultraviolet illumination. The very low dark current of 4.75 × 10⁻¹¹ A provides a low-noise baseline that is essential for achieving high detectivity under weak light conditions. Even at an optical power density as low as 2.47 nW cm⁻², the device exhibits a responsivity of 19.23 A W⁻¹. The corresponding gain and specific detectivity reach 58.80 and 1.22 × 10¹⁴ Jones, respectively. These results confirm the suitability of 2D perovskite single crystals for ultra-weak light photodetection.