Extremely Low Dark Current MoS₂ Photodetector via 2D Halide Perovskite as the Electron Reservoir

Abstract Toward pursuing high‐performance photodetectors based on 2D transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS₂), it is desirable to reduce the high dark current and sluggish response time. Here, in multilayer MoS₂‐based photodetectors, a 2D halide perovskite, (C₆H₅C₂H₄NH₃)₂PbI₄ ((PEA)₂PbI₄), is introduced as a bifunctional material: both as electron reservoir to reduce free carriers and passivation agent to passivate defects. Surprisingly, dark current is suppressed by six orders of magnitude after coating a (PEA)₂PbI₄ thin layer onto pristine MoS₂ photodetector, with the dark current decreased to 10⁻¹¹ A. This huge reduction of dark current suggests an efficient interlayer charge transfer from MoS₂ to (PEA)₂PbI₄, which is further verified by photoluminescence quenching phenomenon. It indicates that (PEA)₂PbI₄ serves as electron reservoir to reduce carrier density of MoS₂, resulting in ultrahigh detectivity (1.06 × 10¹³ Jones). Moreover, the response speed is also accelerated by more than 100‐fold due to passivation by 2D perovskite. In addition, it is found that this type of photodetectors can further work at self‐power mode (with the bias of 0 V). Therefore, the strategy of applying 2D perovskite on the surface of TMDs provides a novel way to fabricate high‐performance photodetectors.