Polarization-sensitive photodetection in a broad spectrum range is highly desired due to the great significance in military and civilian applications. Palladium diselenide (PdSe2), a newly explored air-stable, group 10 two-dimensional (2D) noble metal dichalcogenide with a puckered pentagonal structure, holds promise for polarization-sensitive photodetection. Herein, we report a highly polarization-sensitive, broadband, self-powered photodetector based on graphene/PdSe2/germanium heterojunction. Owing to the enhanced light absorption of the mixed-dimensional van der Waals heterojunction and the effective carrier collection with graphene transparent electrode, the photodetector exhibits superior device performance in terms of a large photoresponsivity, a high specific detectivity, a fast response speed to follow nanosecond pulsed light signal, and a broadband photosensitivity ranging from deep ultraviolet (DUV) to mid-infrared (MIR). Significantly, highly polarization-sensitive broadband photodetection with an ultrahigh polarization sensitivity of 112.2 is achieved, which represents the best result for 2D layered material-based photodetectors. Further, we demonstrated the high-resolution polarization imaging based on the heterojunction device. This work reveals the great potential of 2D PdSe2 for high-performance, air-stable, and polarization-sensitive broadband photodetectors.

An electrically modulated single‐/dual‐color imaging photodetector with fast response speed is developed based on a small molecule (COi8DFIC)/perovskite (CH3NH3PbBr3) hybrid film. Owing to the type‐I heterojunction, the device can facilely transform dual‐color images to single‐color images by applying a small bias voltage. The photodetector exhibits two distinct cut‐off wavelengths at ≈544 nm (visible region) and ≈920 nm (near‐infrared region), respectively, without any power supply. Its two peak responsivities are 0.16 A W−1 at ≈525 nm and 0.041 A W−1 at ≈860 nm with a fast response speed (≈102 ns). Under 0.6 V bias, the photodetector can operate in a single‐color mode with a peak responsivity of 0.09 A W−1 at ≈475 nm, showing a fast response speed (≈102 ns). A physical model based on band energy theory is developed to illustrate the origin of the tunable single‐/dual‐color photodetection. This work will stimulate new approaches for developing solution‐processed multifunctional photodetectors for imaging photodetection in complex circumstances.

We demonstrated a stable and spectrum-selective self-powered UV photodetector based on lead-free Cs3Cu2I5 films with excellent photodetection performance.

Self-powered solar-blind photodetectors based on diamond/β-Ga2O3 heterojunctions have been fabricated and high quality solar-blind images have been realized.

Polarization-sensitive ultraviolet (UV) photodetection is of great technological importance for both civilian and military applications. Two-dimensional (2D) group-10 transition-metal dichalcogenides (TMDs), especially palladium diselenide (PdSe 2 ), are promising candidates for polarized photodetection due to their lowsymmetric crystal structure. However, the lack of an efficient heterostructure severely restricts their applications in UV-polarized photodetection. Here, we develop a PdSe 2 /GaN Schottky junction by in situ van der Waals growth for highly polarization-sensitive UV photodetection. Owing to the high-quality junction, the device exhibits an appealing UV detection performance in terms of a large responsivity of 249.9 mA/W, a high specific detectivity, and a fast response speed. More importantly, thanks to the puckered structure of the PdSe 2 layer, the device is highly sensitive to polarized UV light with a large dichroic ratio up to 4.5, which is among the highest for 2D TMD material-based UV polarization-sensitive photodetectors. These findings further enable the demonstration of the outstanding polarized UV imaging capability of the Schottky junction, as well as its utility as an optical receiver for secure UV optical communication. Our work offers a strategy to fabricate the PdSe 2 -based heterostructure for highperformance polarization-sensitive UV photodetection.