Tailoring of Silver Nanocubes with Optimized Localized Surface Plasmon in a Gap Mode for a Flexible MoS_2 Photodetector

摘要

Although noble metal nanoparticles as nanoantenna have been applied in 2D material-based optoelectronic devices, the impact of their morphologies on device performance is still rarely investigated. In this paper, the tailoring of silica-coated Ag nanocubes with optimized localized surface plasmon in a gap mode for a flexible MoS2 photodetector is demonstrated for the first time. The finite different time domain simulation reveals that the Ag nanocubes with an edge length of 60 nm achieve a maximum electromagnetic field enhancement of 2.8 x 10(6)-fold under excitation of 520 nm incident light, which is about four orders of magnitude higher than that of Ag nanospheres and nanorods. The Ag nanocube modified devices exhibit excellent performance at low operating potential. External photoresponsivity reaches 7940 A W-1 at 3 V under an incident power of 2.2 pW, achieving a 38-fold enhancement compared to the pristine MoS2 photodetector, which is more than one order of magnitude higher than most of the reported MoS2 photodetectors. The flexible devices also display a good mechanical endurance during 10 000 bending cycles. These results indicate that Ag nanocubes coupled with Ag films show great prospect for their application in the field of 2D material-based optoelectronic devices.