Although germanium-and silicon-based detectors have been commercialized for NIR photodetection, [4,5] their response speeds and sensitivities still have potential for improvement. It has also been reported that 2D materials have great potential for application in low-cost, room temperature, and large-area visible-near-infrared (VIS-NIR) photodetection applications owing to their excellent optical and electronic properties, [6][7][8][9][10][11][12] and various VIS-NIR photodetectors based on 2D materials have been reported. For example, graphene has been demonstrated to exhibit a rapid photoresponse; however, its lack of a bandgap, low light absorption properties, and low intrinsic sensitivity hinder its potential applications in VIS-NIR detection. [13,14] As alternatives, transition metal dichalcogenides (TMDs) exhibit large bandgaps for infrared detection, [15,16] and black phosphorus (BP) exhibits a good performance in infrared photodetection owing to its suitable bandgap and fast carrier mobility; [17,18] however, the latter suffers from a poor air stability. Furthermore, despite the fact that heterostructure photodetectors have been shown to exhibit high performances, they require complex transfer processing. [19][20][21] Considering the above systems, it is therefore apparent that the development of suitable VIS-NIR-responsive materials would be highly attractive.In this context, Bi 2 O 2 Se has recently attracted increasing attention because of its suitable electronic bandgap (≈0.8 eV), high carrier mobility (≈450 cm 2 V −1 s −1 at 300 K), excellent air stability, high conductivity, and environmental non-toxicity, which render it an ideal candidate for VIS-NIR detection. [22][23][24][25][26][27][28] However, its high carrier concentration leads to a large dark current in detectors based on Bi 2 O 2 Se nanosheets, which restricts any further performance improvement being achieved. To address this issue, previous studies have examined the use of gate voltage regulation [29,30] and heterostructure construction. [31][32][33] However, the application of extremely high gate voltages increases the power consumption of the device, and the construction of heterostructures often requires complex transfer processes. In addition, the reported Bi 2 O 2 Se photodetectors tend to show poor response speeds in the NIR waveband (i.e., tens of milliseconds), which limits their application in high-speed detection. [27,34] Owing to its suitable electronic bandgap, excellent air stability, and high carrier mobility at room temperature, low-dimensional bismuth oxyselenide (Bi 2 O 2 Se) has become attractive in the context of visible-near-infrared (VIS-NIR) detection. However, the high carrier concentration and bolometric effect of Bi 2 O 2 Se nanosheets are not conducive to reducing the dark current and improving the response speed, which hinders Bi 2 O 2 Se nanosheet-based photodetectors from achieving an optimal performance. In this study, a Bi 2 O 2 Se nanoribbon is controllably synthesized on a fluorophlogopite substrate by m...

PbSe has attracted wide attention owing to its fascinating physical and chemical properties. It has important technical significance for infrared detectors. However, due to the inherent bandgap, low carrier mobility, and dielectric constant of PbSe, it is a significant challenge to realize fast response and mid‐infrared (MID) photodetection. Chemical doping is an efficient method to regulate the band structure and carrier mobility of materials. Nevertheless, the doped film detector cannot satisfy the demands of high‐performance photodetectors. In this paper, different composition ratios powders are synthesized by a solid‐state method. The PbSe0.5Te0.5 alloy film displays narrower bandgap, higher carrier mobility, excellent photo‐response, and broadband detection capacity. By utilizing the above superiority of PbSe0.5Te0.5 and fast charge transfer in MoSe2, a PbSe0.5Te0.5/MoSe2 p‐n heterostructure device is successfully fabricated that has significant rectifying effect (103) and extremely low dark current density (720 µA cm−2). The photodetector has a maximum responsivity (R) and specific detectivity (D*) of 17.5 A W−1 and 3.08 × 1013 Jones at 780 nm. In addition, the detector displays superior photodetection performance with broadband photodetection (405–5000 nm), high switch ratios (Ion/Ioff = 105), and fast response speed. The above outstanding properties indicate that the PbSe0.5Te0.5/MoSe2 heterostructure provides a promising and efficient strategy for achieving a miniaturized, broadband, and high‐performance photodetector.

Due to its unique band structure and topological properties, the 2D topological semimetal exhibits potential applications in photoelectric detection, polarization sensitive imaging, and Schottky barrier diodes. However, its inherent large dark current hinders the further improvement of the performance of the semimetal‐based photodetectors. In this study, a van der Waals (vdWs) field effect transistor (FET) composed of semimetal PdTe2 and transition metal dichalcogenides (TMDs) WSe2 is fabricated, which exhibits high sensitivity photoelectric detection performance in a wide band from visible light (405 nm) to mid‐infrared (5 µm). The dark current and the noise level in the device are greatly suppressed by the effective control of the gate. Benefiting from the extremely low dark current (1.2 pA), the device achieves an optical on/off ratio up to 106, a high detectivity of 9.79 × 1013 Jones and a rapid response speed (219 and 45 µs). This research demonstrates the latent capacity of the 2D topological semimetal/TMDs vdWs FET for broadband, high‐performance, and miniaturized photodetection.