Photoluminescence Enhancement Of MoS₂ With Three-dimensional Photonic Crystals

Due to the periodic arrangement of different refractive index dielectric materials inside the three-dimensional photonic crystal,a photonic forbidden band that prohibits the propagation of light of a specific wavelength will be generated.By changing the structural parameters of the photonic crystal to tune the position of the photonic forbidden band,the electromagnetic wave can be controlled.The slow light effect and photon localization produced by photonic crystals are widely used to enhance the luminescence of fluorescent materials.Molybdenum disulfide,a single layer of semiconductor two-dimensional material,is widely used in light-emitting devices and electronic flexible devices due to its unique optoelectronic properties.However,due to its thickness limitation,the luminous intensity of single-layer molybdenum disulfide is still weak.Therefore,it is of great significance to take measures to enhance the photoluminescence of single-layer molybdenum disulfide.In this dissertation,the photonic crystal's forbidden band effect is used to enhance the photoluminescence of a single layer of molybdenum disulfide.Then,the plasma effect of a photonic crystal and a metal nanostructure is used to enhance the photoluminescence of a single layer of molybdenum disulfide.First,a three-dimensional photonic crystal structure was prepared by the vertical settlement method,and the band gap position was tuned by adjusting its structural parameters.Then,the single-layer molybdenum disulfide prepared by the chemical vapor deposition method is transferred to the surface of the photonic crystal,so that the absorption peak of the molybdenum disulfide coincides with the forbidden band reflection peak of the photonic crystal.The energy transfer of the localized photons on the surface of the photonic crystal and the MoS₂ excitons leads to the Rabi splitting,which greatly increases the concentration of the MoS₂ exciton in the single layer,thus improving the photoluminescence intensity.The photonic crystal was combined with a U-shaped split-ring metal nanostructure array,and the tunable emission characteristics of molybdenum disulfide under the combined effect of the plasma effect of the U-shaped split ring and the band gap of the photonic crystal were calculated by FDTD simulation.The band gap effect increases the concentration of luminescent excitons in molybdenum disulfide,and the plasma effect promotes the luminescent recombination of excitons.In terms of enhancing the photoluminescence of single layer molybdenum disulfide,the combined effect of the above two is greater than that of the photonic crystal band gap alone.