| Quantum dots(QDs)are one of the most important new low-dimensional semiconductor nanomaterials,their unique physico-chemical properties and broad application prospect make them a leader in modern semiconductor materials research.In recent years,colloidal quantum dots(CQDs)are getting more and more attention from people because their adjustable energy gap,preparation methods for solution processing,and multiple exciton production effect.QDs play an important role in many fields,such as new solar photovoltaic cells based on QDs,QDs light-emitting diodes,QDs bioimaging,QDs photodetectors and QDs lasers.But in the current study,the QDs material preparation cost is high,the preparation conditions are harsh,they often need to high temperature and pressure environment and they are difficult to form homogeneous film surface.Therefore,in the frontier research of QDs photodetectors,it is urgent to find a simpler and easier method to prepare QDs photoelectric materials,so as to provide guarantee for subsequent large-scale productionIn this thesis,we adopt a simple,low-cost and green method to synthesize the SnS2 QDs and CuS QDs under the condition of normal pressure and temperature below 80 0C.And then,the morphology,structure and photoelectric properties of the SnS2 QDs and CuS QDs were fully analyzed and discussed through the transmission electron microscope(TEM),atomic force microscope(AFM),scanning electron microscope(SEM),Raman spectroscopy(Raman),X-ray diffraction analysis(XRD),photoluminescence spectroscopy(PL),photoexcitation spectrum(PLE),ultraviolet-visible absorption spectra(UV-Vis),X-ray photoelectron spectroscopy(XPS)and a series of analytical testing technology.The photodetectors based on SnS2 QDs and CuS QDs were prepared.The current and voltage(J-V)curves,responsivity(R)and detection rate(D*).The curves of the resistivity varies with temperature(R-T)and capacitance-voltage(C-V)curves of the two photodetectors were also tested and analyzed.The main research contents and relevant conclusions of this paper are as follows:(1)Take sulfur precursor and metal precursors(Sn and Cu)as raw material,using CQDs synthesis methods under the condition of normal pressure and temperature no more than 80 ? to prepare the SnS2 QDs and CuS QDs.The average particle size of SnS2 QDs obtained was 4.2 nm,and the average particle size of CuS QDs was 6.5 nm.Both kinds of quantum dots have good monodispersity and homogeneity.The formation of two QDs with three different concentrations was compared,respectively,and it was found that the monodispersity and homogeneity of the QDs solutiorn with 0.2 mol·L-1 were the best.Raman spectrum studied the vibration modes of both kinds of quantum dots:Eg and Alg,and Alg vibration mode is the main mode.The energy gap of SnS2 QDs fitted by Tauc was 3.47 eV,and the energy gap of CuS QDs was 2.30 eV,and their band gaps were larger than those of bulk materials,and the reasons were analyzed.Both QDs exhibited good photoluminescence properties.(2)The photoelectric detector based on SnS2 QDs was responsive to ultraviolet light(X,=365 nm),and the responsivity was 0.10 A·W-1 and the detection rate was stable at 1011 Jones.The photoelectric detector based on CuS QDs was responsive to infrared light(?=850 nm),and its responsivity(300 A.w-1)was larger than which of SnS2 QDs optoelectronic devices,and its detection rate was stable at 1013 Jones.Both photoelectric detectors showed stable photoelectric detection performance,which is expected to be applied in the field of photoelectric detection.At room temperature,the resistivity of the two photodetectors increased with the temperature,and the thermal activation energy(Ea)of the two photoelectric devices was discussed.The C-Vcurves of the two photodetectors were also different,and their built-in potential(Vb;),carrier concentration(N),and depletion layer width(Wd)were discussed,these data will provide some scientific basis for the development of two QDs optoelectronic devices. |
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