Decorating MoS₂ Nanoscrolls with Solution-Processed PbI₂ Nanocrystals 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 PbI2 nanocrystals were first deposited on a monolayer MoS2 nanosheet grown by chemical vapor deposition using a solution processing method (referred to as PbI2/MoS2). After PbI2/MoS2 was immersed into a mixture of ammonia and isopropanol, PbI2/MoS2 nanoscrolls with sizes of up to several tens of micrometers were formed in a short time. The density of PbI2 nanocrystals on the MoS2 nanosheet was highly dependent on the concentration and immersion time in PbI2 solution. Atomic force microscopy, optical microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to characterize the PbI2/MoS2 nanosheet and nanoscroll. The as-prepared PbI2/MoS2 nanosheet and nanoscroll showed photosensitivities 2 orders of magnitude higher than those of the MoS2 nanosheet and nanoscroll in visible light, which could be attributed to the type II heterointerface in the PbI2/MoS2 nanosheet and multiple PbI2/MoS2 heterointerfaces in the scrolled structure. Our work indicates that the PbI2 nanocrystal-decorated MoS2 nanoscroll could be a promising candidate for high-performance optoelectronic devices.