Abstract
Photodetectors based on two-dimensional (2D) materials have great potential applications in the field of new energy, such as fuel cells, solar cells, and other fields. Van der Waals (vdW) heterojunction photodiodes are expected to be one of the promising applications of two-dimensional materials due to the photoelectric properties without consideration of lattice mismatch. High-efficiency photoelectric sensors based on two-dimensional materials have great significance to reducing the energy consumption of devices. Here, we build a complex vdW heterostructure by combining InS0.3Se0.7 with another suitable 2D material WS2. Few-layer graphite was used as electrodes to enhance the optoelectronic performance of indium monochalcogenides. Evident photocurrent is observed in the InS0.3Se0.7/WS2 vdW heterostructure device arising from the formed p–n junction at the interface. The uniformity and photoresponse of the InS0.3Se0.7/WS2 vdW heterostructure has been further investigated by the photocurrent mapping. It shows that the entire photovoltaic current was originated from the InS0.3Se0.7/WS2 vdW heterojunction by scanning photocurrent microscope images. Furthermore, the response speed is enhanced at small bias voltage. The transient photoresponse can be well reproduced in almost 100 cycles, indicating the good repeatable optoelectronic performance. Our study indicates that the as-prepared InS0.3Se0.7/WS2 vdW heterostructures are attractive building blocks for photodetectors application. Our findings will open up a new way to further develop high-performance, low-power, and energy-efficient photodetectors based on indium monochalcogenides.
Highlights
(2D) materials is expected to solve the energy problem, which is caused by the huge growth of the number of sensors bringing by high integration and smaller size of electronic devices [1,2,3,4]. 2D semiconductor devices with low power consumption and high performance can be widely used in new energy fields, such as photocatalysis, fuel cells, solar cells, and others [3,5,6,7,8,9,10,11]
The scanning electron microscopy (SEM) image (Figure S2a) of the as-synthesized InS0.3 Se0.7 crystals are of layered structures, energy-dispersive X-ray spectroscopy (EDS) (Figure S2b–e) shows the elements of In, S, and Se evenly spread and the atomic ratio of In, S, and Se elements is estimated to be about 1:0.3:0.7
WS2, demonstrating that the two graphene electrodes do enhance the photoresponse by contributing efficient carriers. This phenomenon further demonstrates that the measured photocurrent in our InS0.3 Se0.7 /WS2 Van der Waals (vdW) heterostructure devices is originated from the p–n junction formed at the interface, in which the photo-generated electron–hole pairs are effectively separated by the built-in field of the p–n junction
Summary
The development of advanced semiconductors based on two-dimensional (2D) materials is expected to solve the energy problem, which is caused by the huge growth of the number of sensors bringing by high integration and smaller size of electronic devices [1,2,3,4]. 2D semiconductor devices with low power consumption and high performance can be widely used in new energy fields, such as photocatalysis, fuel cells, solar cells, and others [3,5,6,7,8,9,10,11]. The photoelectric properties of a type II vdW heterostructure based on InS0.3 Se0.7 /WS2 were investigated.
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