The Preparation And Optical Properties Of Molybdenum Selenide Two-dimensional Materials Related Heterojunctions

Molybdenum selenide?MoSe₂?is a layered super metallic sulphide material,which is easy to be peeled off to form monolayer or multilayer MoSe₂ two-dimensional materials.It can be used to fabricate transistors and photovoltaic devices because of its strong light absorption and high photoelectric conversion efficiency.In addition,MoSe₂ can form van der Waals heterojunctions by combing with graphene and other transition metal sulfides.Such heterojunctions can be used to prepare new solar cells,photodetectors and related devices for their high photoelectric gain and large response range.In the present studies,the graphene/MoSe₂ heterojunction and MoS₂/MoSe₂ heterojunctions were prepared,and the effects of growth conditions and doping on the heterojunction structure and photoelectric properties of the heterojunctions were investigated.The results will provide some experimental basis for the preparation of MoSe₂ heterojunctions optoelectronic devices.1.Fabrication and study of the optoelectronic properties of the graphene/MoSe₂heterojunction.Methane,MoSe₂ saturated solution were used as the raw materials,and Ar gas as carrying gas.MoSe₂ film was prepared on silicon substrates by chemical vapor deposition?CVD?using Ar gas carried MoSe₂ vapor molecule into the chamber to deposit MoSe₂ film,then graphene film was deposited on MoSe₂ film by input CH₄.CH₄ is decomposed and deposited on the surface of MoSe₂ film at high temperature to form graphene/MoSe₂ heterojunction.The surface morphology and crystal structure of the films and the heterojunctions Atomic force microscopy?AFM?and X-ray diffraction were used to characterize.It was found that the graphene and molybdenum selenide thin films prepared by this method were uniform and had good crystal structure.The photoelectric properties of the films and heterojunctions were measured by UV-3600 spectrophotometer and I-V test system.It was found that the heterojunction device had good voltaic properties.After doping with silver,the surface of MoSe₂ thin films tends to grow into nanowires,the conductivity of heterojunctions and the optical absorption of heterojunctions are enhanced significantly due to the catalytic and good optical absorption properties of silver,which can be used to prepare high-efficiency solar cells and photovoltaic detectors.2.Fabrication and study of the optoelectronic properties of the Ag-doped heterojunctionsgraphene/MoSe₂heterojunction.Silver-dopedgraphene/MoSe₂heterojunction was formed by adding silver nitrate saturated vapor into the growth process of Mose₂ thin films with silver nitrate solution as dopant.Because of the catalytic and good light absorption properties of silver,it was found that the surface of MoSe₂ tended to grow columnarly after silver doping,and the conductivity of heterojunctions was enhanced significantly.It can be used to prepare high-efficiency solar cells,photovoltaic detectors and so on.3.Fabrication and study of the photoelectric properties of MoS2/MoSe2heterojunctions.MoS₂/MoSe₂ heterojunction was formed on MoS₂ thin films prepared by argon-supported MoS2 molecule growth from MoS2 saturated solution.It is found that MoS2/MoSe2 heterojunctions have good electrical properties,which indicates that different transition sulfides can form interfaces with fewer defects,fewer interface states and better contacts through van der Waals force bonding,which is very useful to the preparation of electronic devices with good cross-section characteristics.In addition,it was found that MoS2/MoSe2 heterojunction has good absorption and photocurrent properties in the visible range.It can be used to fabricate MoS₂/MoSe₂ heterojunction optoelectronic devices.In summary,MoSe₂ two-dimensional materials and related heterojunctions have the characteristics of strong light absorption,fast photoelectric response and remarkable photovoltaic effect.The results of this study have a good guiding significance for the preparation of two-dimensional material-related heterojunctions based on MoSe₂ as photovoltaic devices such as solar cells,photosensitive devices and photodetectors.