Decorating MoS₂Nanoscrolls with Solution-Processed PbI₂Nanocrystals for Improved Photosensitivity

Despite their excellent properties, the low light absorption efficiency of atomically thin transition metal dichalcogenide (TMDC) nanosheets limits their application in optoelectronics. Many efforts have been devoted to enhance the light-matter interaction of the TMDC nanosheets. Among them, coupling the TMDC nanosheet with photoactive materials has drawn extensive attention. Recently, forming one-dimensional nanoscrolls from monolayer TMDC nanosheets has also been proven to be an effective way of improving the photodetection performance of TMDC nanosheets. Herein, photoactive PbI₂nanocrystals were first deposited on a monolayer MoS₂nanosheet grown by chemical vapor deposition using a solution processing method (referred to as PbI₂/MoS₂). After PbI₂/MoS₂was immersed into a mixture of ammonia and isopropanol, PbI₂/MoS₂nanoscrolls with sizes of up to several tens of micrometers were formed in a short time. The density of PbI₂nanocrystals on the MoS₂nanosheet was highly dependent on the concentration and immersion time in PbI₂solution. Atomic force microscopy, optical microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to characterize the PbI₂/MoS₂nanosheet and nanoscroll. The as-prepared PbI₂/MoS₂nanosheet and nanoscroll showed photosensitivities 2 orders of magnitude higher than those of the MoS₂nanosheet and nanoscroll in visible light, which could be attributed to the type II heterointerface in the PbI₂/MoS₂nanosheet and multiple PbI₂/MoS₂heterointerfaces in the scrolled structure. Our work indicates that the PbI₂nanocrystal-decorated MoS₂nanoscroll could be a promising candidate for high-performance optoelectronic devices.