摘要： 2D layered materials are an emerging class of low-dimensional materials with unique physical and structural properties and extensive applications from novel nanoelectronics to multifunctional optoelectronics. However, the widely investigated 2D materials are strongly limited in high-performance electronics and ultrabroadband photodetectors by their intrinsic weaknesses. Exploring the new and narrow bandgap 2D materials is very imminent and fundamental. A narrow-bandgap noble metal dichalcogenide (PtS2) is demonstrated in this study. The few-layer PtS2 field-effect transistor exhibits excellent electronic mobility exceeding 62.5 cm2 V?1 s?1 and ultrahigh on/off ratio over 106 at room temperature. The temperature-dependent conductance and mobility of few-layer PtS2 transistors show a direct metal-to-insulator transition and carrier scattering mechanisms, respectively. Remarkably, 2D PtS2 photo detectors with broadband photodetection from visible to mid-infrared and a fast photoresponse time of 175 μs at 830 nm illumination for the first time are obtained at room temperature. Our work opens an avenue for 2D noble-metal dichalcogenides to be applied in high-performance electronic and mid-infrared optoelectronic devices.