Molybdenum Disulfide Nanoribbons with Enhanced Edge Nonlinear Response and Photoresponsivity.

MoS 2 nanoribbons have attracted an increased interest due to their properties, which can be tailored by tuning their dimensions. Herein, we demonstrate the growth of MoS 2 nanoribbons and 3D triangular crystals formed by the reaction between ultra-thin films of MoO 3 grown by Pulsed Laser Deposition and NaF in a sulfur-rich environment. The multilayer nanoribbons can reach up to 10 μm in length, and feature single-layer edges, forming a monolayer-multilayer MoS 2 junction enabled by the lateral modulation in thickness. The single-layer edges of the nanoribbons show a pronounced second harmonic generation due to the symmetry breaking, in contrast to the centrosymmetric multilayer structure, which is unsusceptible to the second-order nonlinear process. A pronounced splitting of the Raman spectra was observed in MoS 2 nanoribbons arising from distinct contributions from the monolayer edges and multilayer core. Nanoscale imaging reveals a blue-shifted exciton emission of the monolayer edge compared to the triangular MoS 2 monolayers due to built-in local strain and disorder. We further report on an ultrasensitive photodetector made of a single MoS 2 nanoribbon with a responsivity of 8.72×10 2 A/W at 532 nm, among the highest reported up-to-date for single-nanoribbon photodetectors. Our findings can inspire the design of MoS 2 semiconductors with tunable geometries for efficient optoelectronic devices. This article is protected by copyright. All rights reserved.