| Graphene-like molybdenum disulfide(MoS2)is one of the typical two-dimensional nanomaterials.Because of its good thermal stability,chemical stability,mechanical strength,flexibility,transparency and carrier mobility,it is widely used in optoelectronic devices,biosensing,energy storage and other fields have huge application potential.The functionalized Mo S2 will further broaden its application in the field of optoelectronic devices,so the preparation of Mo S2 based nanocomposites and their applications in the field of optoelectronic devices endowed with high research value.Based on this,this thesis takes MoS2-based nanocomposites as the main research object,and optimizes its liquid phase exfoliation method,which improves the yield of few layer Mo S2 nanosheets.Under these conditions,Mo S2works as a template.Then Mo S2-pectin nanocomposites and Mo S2-carbon dots nanocomposites were prepared for nonvolatile memory devices.Meanwhile,the performance of memory devices were improved through the optimization of relevant conditions.This thesis will carry out research the following two aspects:First,semiconductor MoS2-pectin nanocomposites were prepared by liquid phase ultrasonic method.Transmission electron microscope(TEM),UV-visible spectrophotometer were used to characterize the absorption spectrum,and the preparation conditions were optimized.It was found that the optimum conditions were as follows:ultrasonic time 3.0 h,ultrasonic solvent deionized water,weight ratio of Mo S2/pectin 10:1.Then,by spin-coating and evaporation,the nanocomposites were used as active layer for nonvolatile memory devices.The threshold voltage is about 1.8 V,the switching ratio is about 5×102,and the retention time is more than 104 seconds.The device can perform 20 stable write-ease-read-ease(WERE)cycles.This method has great reference value for the preparation of Mo S2-based nanocomposites and its application in nanoelectronic devices.Second,MoS2-carbon dots nanocomposites were prepared through surface deposition(SD)method.A new kind of carbon dots with phosphorescence lifetime exceeding 400 ms were prepared by hydrothermal method.The fluorescence and phosphorescence properties of carbon dots were investigated under the conditions of different ratio of carbon/nitrogen,carbonization temperature and hydrothermal reaction time.The optimum reaction conditions were as follows:the molar ratio of carbon source to nitrogen source was 2:3,the reaction temperature was 200?,and the reaction time was 12 h.The synthesized carbon dots were characterized by UV-Vis absorption spectra and steady-state transient fluorescence system.The carbon dots have good response to the light in the wavelength range of 200 nm to 450 nm.Under the excitation of 365 nm handheld UV light source,blue fluorescence and bright orange afterglow can be observed,lasting about 10 s,which provides a broader possibility for the application of carbon dots as new phosphorescent materials in the field of optoelectronics.Based on this kind of carbon dots,Mo S2-carbon dots nanocomposites were prepared through SD method.The nanocomposites were characterized by TEM and XRD.Finally,through spin-coating and evaporation,the nanomaterials worked as the active layer for the nonvotile memory devices.The devices exhibited Flash storage characteristics with the current switch ratio is over 102order of magnitude.This method provides an empirical support for the application of Mo S2-based memory devices. |
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