2D material based photodetectors have attracted many research projects due to their unique structures and excellent electronic and optoelectronic properties. These 2D materials, including semimetallic graphene, semiconducting black phosphorus, transition metal dichalcogenides, insulating hexagonal boron nitride, and their various heterostructures, show a wide distribution in bandgap values. To date, hundreds of photodetectors based on 2D materials have been reported. Here, a review of photodetectors based on 2D materials covering the detection spectrum from ultraviolet to infrared is presented. First, a brief insight into the detection mechanisms of 2D material photodetectors as well as introducing the figure-of-merits which are key factors for a reasonable comparison between different photodetectors is provided. Then, the recent progress on 2D material based photodetectors is reviewed. Particularly, the excellent performances such as broadband spectrum detection, ultrahigh photoresponsivity and sensitivity, fast response speed and high bandwidth, polarization-sensitive detection are pointed out on the basis of the state-of-the-art 2D photodetectors. Initial applications based on 2D material photodetectors are mentioned. Finally, an outlook is delivered, the challenges and future directions are discussed, and general advice for designing and realizing novel high-performance photodetectors is given to provide a guideline for the future development of this fast-developing field.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201803807. atomic layer, while these atomically thin layers are bonded together by weak van der Waals interactions along the third dimension perpendicular to the 2D plane. The weak interlayer interaction makes it possible to exfoliate bulk crystals into isolated thin 2D flakes and even a single atomically thin layer.A photodetector is a device that can convert a light signal into an electrical signal. High performance photodetectors play important roles in many fields of our daily life, including electro-optical displays, imaging, environment monitoring, optical communication, military, security checking and so forth. 2D materials, as one of most competitive materials for designing photodetectors, have been demonstrated with remarkable characteristics, including broad detection waveband covering the wavelengths from UV to terahertz frequencies (THz, 10 12 Hz), ultrahigh photoresponsivity, polarization sensitive photodetection, high-speed photoresponse, high spatially resolved imaging, etc. Thanks to the recently developed dry transfer technique, [1] various heterostructures based on 2D materials have been designed and fabricated with desirable band alignments. Photodetectors based on these heterostructures have exhibited enhanced performances like high photovoltaic external quantum efficiency up to 30% for graphene-WS 2 -graphene, [2] ultrahigh photoresponsivity up to ≈10 10 A W −1 for graphene-MoS 2 , [3] ultrahigh photogain ...

Low dimensional materials including quantum dots, nanowires, 2D materials, and so forth have attracted increasing research interests for electronic and optoelectronic devices in recent years. Photogating, which is usually observed in photodetectors based on low dimensional materials and their hybrid structures, is demonstrated to play an important role. Photogating is considered as a way of conductance modulation through photoinduced gate voltage instead of simply and totally attributing it to trap states. This review first focuses on the gain of photogating and reveals the distinction from conventional photoconductive effect. The trap‐ and hybrid‐induced photogating including their origins, formations, and characteristics are subsequently discussed. Then, the recent progress on trap‐ and hybrid‐induced photogating in low dimensional photodetectors is elaborated. Though a high gain bandwidth product as high as 109 Hz is reported in several cases, a trade‐off between gain and bandwidth has to be made for this type of photogating. The general photogating is put forward according to another three reported studies very recently. General photogating may enable simultaneous high gain and high bandwidth, paving the way to explore novel high‐performance photodetectors.

Black arsenic phosphorus–based photodetectors sense detect long-wave mid-infrared light with high detectivity at room temperature.