Nonlinear Optical Properties Of MoSe₂ And Its Composites

In the electronic information era,transition metal sulfides（TMDs）are increasingly widely used in the field of optoelectronic devices.Therefore,it is necessary to explore and study the optical properties of TMDs.Molybdenum selenide（MoSe₂）has many excellent optical properties in TMDs,such as small band gaps,strong exciton properties,and so on.In this paper,the nonlinear absorption characteristics of MoSe₂ nanoflakes and MoSe₂ nanofilms have been successfully prepared and discussed.The introduction of metals will accelerate the carrier mobility within semiconductor materials,so the composite situation of Ag nanofilms with MoSe₂ nanoflakes and MoSe₂ nanofilms was further discussed.The sample composition,micromorphology,linear and nonlinear optical properties were characterized and explored.The main research results are as follows:MoSe₂ nano-sheet mixture was successfully prepared using ultrasonic liquid phase assisted stripping method.MoSe₂ nanofilms and Ag nanofilms were successfully prepared using magnetron sputtering technology.Ag/MoSe₂ nanocomposite materials were successfully prepared using spin coating method and magnetron sputtering technology.Ag/MoSe₂ composite films were successfully prepared using magnetron technology in two steps.The samples were characterized and analyzed by field emission electron microscopy,transmission electron microscopy,and other technical means.The results of X-ray photoelectron spectroscopy（XPS）analysis indicate that MoSe₂ nanosheets have been successfully prepared.The results of transmission electron microscopy show that the grain size of MoSe₂ thin films increases significantly with the increase of sputtering power.The ultraviolet visible absorption spectra of Ag/MoSe₂ composite films were analyzed,and it was found that the optical band gap of Ag/MoSe₂composite films decreased with the increase of Ag sputtering power.The sample was tested using an open-hole Z-scan,and the results showed that the nonlinear absorption type of the sample was saturated absorption.The concentration of MoSe₂ nano-sheet and the sputtering power of MoSe₂ have an impact on the saturation absorption strength.The increase in sputtering power of Ag nano thin films has an inhibitory effect on saturation absorption.Changes in the energy of the excitation light source have an impact on the saturated absorption characteristics.The electron transfer mechanism diagram of Ag/MoSe₂ composite thin film was drawn to scientifically explain the nonlinear absorption mechanism of the prepared sample.It has been proved that the composite of Ag nano films can significantly improve the nonlinear optical properties of MoSe₂ nano materials,expanding the application of MoSe₂ in the field of optoelectronic devices.