Tailoring MoS₂ Valley‐Polarized Photoluminescence with Super Chiral Near‐Field

Abstract

Transition metal dichalcogenides with intrinsic spin-valley degrees of freedom hold great potentials for applications in spintronic and valleytronic devices. MoS monolayer possesses two inequivalent valleys in the Brillouin zone, with each valley coupling selectively with circularly polarized photons. The degree of valley polarization (DVP) is a parameter to characterize the purity of valley-polarized photoluminescence (PL) of MoS monolayer. Usually, the detected values of DVP in MoS monolayer show achiral property under optical excitation of opposite helicities due to reciprocal phonon-assisted intervalley scattering process. Here, it is reported that valley-polarized PL of MoS can be tailored through near-field interaction with plasmonic chiral metasurface. The resonant field of the chiral metasurface couples with valley-polarized excitons, and tailors the measured PL spectra in the far-field, resulting in observation of chiral DVP of MoS -metasurface under opposite helicities excitations. Valley-contrast PL in the chiral heterostructure is also observed when illuminated by linearly polarized light. The manipulation of valley-polarized PL in 2D materials using chiral metasurface represents a viable route toward valley-polaritonic devices.

Functionalized Hybridization of 2D Nanomaterials

“…[111] Also, the mixed solution of Au nanoparticles and MoS 2 nanosheets was incubated to assemble them into hybrids, and further drop-casted on gold electrode after removing the nonassembled ones by centrifugation to show higher current density/electron mobility and faster mass transport. [115] More interestingly, Fang's group used electron beam lithography and thermal evaporation method to fabricate various gold structures on CVD-grown MoS 2 monolayers, such as nanodisks, [116] spiral ring, [117] chiral pattern, [118] grating array, [119] and nanoantenna. [113] The heterostructure of p-GaTe/n-MoS 2 exhibited an excellent photovoltaic and photodetecting performance, including a rectification ratio of 4 × 10 5 , an external quantum efficiency of 61.68% and a photoresponsivity of 21.83 A W −1 .…”

Tailoring the spatial localization of bound state in the continuum in plasmonic-dielectric hybrid system

“…[10], as fabricating a uniform nanometer scale film is still challenging. Such sub-nanoscale layer can be substituted by 2D materials, which have been demonstrated recently [42]. Note that this proposed effect is valid when taking the absorption of Si in the visible spectrum into account [43].…”

Hybridizing Plasmonic Materials with 2D‐Transition Metal Dichalcogenides toward Functional Applications

“…The PL intensity of monolayer MoSe 2 can be manipulated from nearly fourfold quenching to approximately threefold enhancement by the introduction of a spacer layer between the monolayer MoSe 2 and plasmonic nanoantenna. The dominant reason for PL quenching without spacer is the increased nonradiative decay emission from the MoSe 2 placed in proximity of the plasmonic nanoantenna 155. The architecture of hybrid monolayer MoSe 2 coupled to plasmonic nanostructures with and without spacer is shown in a schematic diagram in Figure 14c.…”