Lead-Based Perovskites Significantly Suppress Dark Currents toward High-Performance Multilayer SnS₂/Perovskite Photodetectors

Tin disulfide (SnS₂), a layered material analogous to two-dimensional transition metal dichalcogenides (TMDs), demonstrates excellent photoresponse capabilities. However, the relatively large dark current in multilayer SnS₂ photodetectors limits their potential in high-performance photodetection. To address this issue, we introduce lead (Pb)-based halide perovskites as dark current suppression layers for the SnS₂ photodetector. Specifically, to evaluate the effects of short- and long-chain organic molecules outside the perovskite octahedral structure [PbI₆]^4-, three-dimensional perovskite cesium-doped formamidinium lead trihalide (FA_0.9Cs_0.1PbI₃) and two-dimensional perovskite phenylethylammonium lead iodide ((PEA)₂PbI₄) were selected as dark current suppression layers, significantly suppressing the dark current while enhancing the device's light on/off ratio and specific detectivity. Results show that, compared to the original SnS₂ photodetector, the proposed device achieves a 5-order magnitude reduction in dark current (down to ∼ 10 pA level), a 150-fold increase in light on/off ratio, a 20-fold improvement in response speed, and a 4-fold enhancement in specific detectivity. Additionally, this device also exhibits notable self-powered photodetection capabilities (operating at 0 V bias). Evidently, the innovative approach of applying a thin Pb-based perovskite layer onto TMD-like materials offers a promising route to develop high-performance photodetectors with low dark current.