Highly Efficient, Ultrabroad PdSe2 Phototransistors from Visible to Terahertz Driven by Mutiphysical Mechanism.

The noble transition metal dichalcogenide palladium diselenide (PdSe2) is an ideal candidate material for broad-spectrum photodetection owing to the large bandgap tunability, high mobility, low thermal conductivity, and large Seebeck coefficient. In this study, self-powered ultrabroadband PdSe2 photodetectors from the visible-infrared to terahertz (THz) region driven by a mutiphysical mechanism are reported. In the visible-infrared region, the photogenerated electron-hole pairs in the PdSe2 body are quickly separated by the built-in electric field at the metal-semiconductor interface and achieve a photoresponsivity of 28 A·W-1 at 405 nm and 0.4 A·W-1 at 1850 nm. In the THz region, PdSe2 photodetectors display a room-temperature responsivity of 20 mA·W-1 at 0.10 THz and 5 mA·W-1 at 0.24 THz based on efficient production of hot carriers in an antenna-assisted structure. Owing to the fast response speed of ∼7.5 μs and low noise equivalent power of ∼900 pW·Hz-1/2, high-resolution transmission THz imaging is demonstrated under an ambient environment at room temperature. Our research validates the great potential of PdSe2 for broadband photodetection and provides a possibility for future optoelectronic applications.