Spatially Heterogeneous Optical Emission from MoSe₂ Nanoribbons

In order to fully exploit the unique physical properties of 2D materials, one must precisely control their dimensionality, composition, strain state, and edge structure. Achieving these goals through a rational chemical synthesis strategy is a compelling but challenging prospect. Here we present detailed optoelectronic characterization of atomically-thin MoSe₂ nanoribbons synthesized through a directed growth strategy on phosphine treated Si surfaces. Temperature-dependent photoluminescence studies reveal both systematic shifts in the emission energy of the MoSe₂ nanoribbons relative to their 2D monolayer counterparts, and previously unobserved regular spatial variations in the photoluminescence intensity across the nanoribbon crystals. Transport measurements on a MoSe₂ nanoribbon field-effect transistor device are used to examine how edge effects manifest in changes of the channel and Hall conductance. This study pushes the boundaries of 2D materials synthesis by revealing that precise control over the structural attributes (dimensionality and edge states) of these crystals gives rise to unprecedented physical properties, and thereby paves the way for harnessing their novel phenomena to advance optics, electronics, and quantum sensing.