Journal
SCIENCE CHINA-MATERIALS
Volume 65, Issue 4, Pages 1000-1011Publisher
SCIENCE PRESS
DOI: 10.1007/s40843-021-1820-y
Keywords
SnS2/Bi2Se3; SnS2/Bi2Te3; type-I heterostructure; type-II heterostructure; photoelectric response; photodetector
Categories
Funding
- National Natural Science Foundation of China [12074311, 11774288, 11974279]
- Natural Science Foundation of Shaanxi Province [2019JC-25]
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Heterostructures based on SnS2/Bi2X3 (X = Se, Te) van der Waals heterostructures grown through a combination of physical vapor deposition and chemical vapor deposition show improved photoelectric properties and responses. The successful design of type-I SnS2/Bi2Se3 and type-II SnS2/Bi2Te3 heterostructures greatly enhances the charge carrier transportation and interface dynamics, leading to a significant increase in photocurrent densities. Explained improvements in photoelectric performance include effective charge separation, enhanced charge-transfer efficiency and carrier density at the interface, and expanded light absorption range. Additionally, the vertical SnS2 enhances light trapping efficiency, with the type-I SnS2/Bi2Se3 heterostructure exhibiting higher photoelectric response compared to the type-II SnS2/Bi2Te3 heterostructure due to more efficient charge transportation at the type-I interface. These results suggest the potential development of high-performance photodetectors and other optoelectronic devices through suitable heterostructures.
Heterostructures based on new advanced materials offer a cornerstone for future optoelectronic devices with improved photoelectric performance. Band alignment is crucial for understanding the mechanism of charge carrier transportation and interface dynamics in heterostructures. Herein, we grew SnS2/Bi2X3 (X = Se, Te) van der Waals heterostructures by combining physical vapor deposition with chemical vapor deposition. The band alignment, measured by high-resolution X-ray photoelectron spectroscopy, suggested the successful design of type-I SnS2/Bi2Se3 and type-II SnS2/Bi2Te3 heterostructures. The SnS2/Bi2X3 heterostructure greatly improved the photoelectric response of a photoelectrochemical-type photodetector. The photocurrent densities in the type-I SnS2/Bi2Se3 and type-II SnS2/Bi2Te3 heterostructure-based devices were more than one order of magnitude higher than those of SnS2, Bi2Se3, and Bi2Te3. The improved photoelectric properties of the SnS2/Bi2X3 heterostructures can be explained as follows: (i) the photoexcited electrons and holes are effectively separated in the heterostructures; (ii) the charge-transfer efficiency and carrier density at the interface between the SnS2/Bi2X3 heterostructures and the electrolyte are greatly improved; (iii) the formed heterostructures expand the light absorption range. The photoelectric performance was further enhanced by efficient light trapping in the upright SnS2. The photoelectric response is higher in the type-I SnS2/Bi2Se3 heterostructure than in the type-II SnS2/Bi2Te3 heterostructure due to more efficient charge transportation at the type-I SnS2/Bi2Se3 heterostructure/electrolyte interface. These results suggest that suitable type-I and type-II heterostructures can be developed for high-performance photodetectors and other optoelectronic devices.
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